In this paper,two types of copper-aluminum heterogeneous electrode plates are stacked and the finite element analysis(FEA)models of two different laser welding conditions are built by using SYSWELD welding simulation ...In this paper,two types of copper-aluminum heterogeneous electrode plates are stacked and the finite element analysis(FEA)models of two different laser welding conditions are built by using SYSWELD welding simulation software to calculate the depth of the welding bead and the temperature distribution of the welding surface.Then,the residual stress analysis data of the welded area are exported and the residual stress is applied to the welded specimen for CAE analysis to ensure that the welding bonding strength meets the design target of a shear force of 500 N or higher.The copper-aluminum laser-stacking simulation technique in this paper can be applied to the manufacturing of copper-aluminum heterogeneous laser-welded electrodes and series-connected electrodes of automotive lithium-ion power battery modules,providing an effective analysis method for welding bonding-strength.展开更多
High-quality bonding of 4-inch GaAs and Si is achieved using plasma-activated bonding technology.The influence of Ar plasma activation on surface morphology is discussed.When the annealing temperature is 300℃,the bon...High-quality bonding of 4-inch GaAs and Si is achieved using plasma-activated bonding technology.The influence of Ar plasma activation on surface morphology is discussed.When the annealing temperature is 300℃,the bonding strength reaches a maximum of 6.2 MPa.In addition,a thermal stress model for GaAs/Si wafers is established based on finite element analysis to obtain the distribution of equivalent stress and deformation variables at different temperatures.The shape varia-tion of the wafer is directly proportional to the annealing temperature.At an annealing temperature of 400℃,the maximum protrusion of 4 inches GaAs/Si wafers is 3.6 mm.The interface of GaAs/Si wafers is observed to be dense and defect-free using a transmission electron microscope.The characterization of interface elements by X-ray energy dispersion spectroscopy indi-cates that the elements at the interface undergo mutual diffusion,which is beneficial for improving the bonding strength of the interface.There is an amorphous transition layer with a thickness of about 5 nm at the bonding interface.The preparation of Si-based GaAs heterojunctions can enrich the types of materials required for the development of integrated circuits,improve the performance of materials and devices,and promote the development of microelectronics technology.展开更多
The objective of this experimental study is to improve the cementing bond quality of sandstone oil-gas well along the wellbore cement-formation interface(WCFI),so as to ensure long-term zonal isolation throughout the ...The objective of this experimental study is to improve the cementing bond quality of sandstone oil-gas well along the wellbore cement-formation interface(WCFI),so as to ensure long-term zonal isolation throughout the lifecycle of the well by using NsO solution as filtercake modifier which was developed in the laboratory.According to designed experimental method and API RP 10,the effectiveness of filtercake modifier(NSO)on the bonding strength at the WCFI was assessed by using designed simulated wellbore as sandstone formation.The experimental results indicated that the samples which were treated with NsO solution had higher bond strength over untreated samples.The strength generally increased with curing period as for treated samples,0.198,0.374,0.433 and 0.473 MPa for 3,7,15,and 30 days respectively while for the untreated samples the bond strength were 0.050,0.070,0.81 and 0.100 MPa for the same period.The water-based filtercake modification techniques had significantly enhanced the bonding strength of WCFI by increasing rates above 296%.Improvement of bond strength to the treated sample was due to filtercake modification as a result of formation of cementitious material as revealed in FTIR spectral such as Calcium-Silicate-Hydrate(C-S-H)and other geopolymers like Calcium-Aluminium-Silicate-Hydrate(C-A-S-H)and Sodium-Aluminium-Silicate-Hydrate(N-A-S-H)along the interface which filled the existed pores hence reducing porosity hence high strength of bond.The low transmittance value for the NsO treated samples revealed that there were more cementitious materials existing at the WCFI which led to improvement of bonding strength as compared to the untreated samples.The lower/poor bond strength for the untreated samples is due to existence of untreated,thick water-based filtercake films at WCFI,which prevented the complete hydration process between rock grains and cement slurry components to make chemical binder of cement slurry material and formation.2022 The Authors.Publishing services provided by Elsevier B.V.on behalf of KeAi Communication Co.Ltd.This is an open access article under the cc BY license(http://creativecommons.org/licenses/by/4.o/).展开更多
Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder...Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder bed fusion(LPBF).The effect of laser process parameters on interfacial defects was evaluated by X-ray tomography,which indicates a low porosity level of 0.042%therein.Gradient/fine dendritic grains in the interface are incited by high cooling rates,which facilitates interface strengthening.Multiple mechanical tests evaluate the bonding reliability of interface;and the fatigue tests further substantiate the ultrahigh bonding strength in FGMs,which is superior to traditional manufacturing methods.Mechanisms of the high interfacial bond strength were also discussed.展开更多
To gain high efficiency and low fuel consumption, aluminum-based abradable seal coatings had been widely used in the compressor casing of aero engines or gas turbines owing to the low elastic modulus. However, the adh...To gain high efficiency and low fuel consumption, aluminum-based abradable seal coatings had been widely used in the compressor casing of aero engines or gas turbines owing to the low elastic modulus. However, the adhesive transfer phenomenon frequently occurs when the radial rubbing generates between titanium alloy blade tips and aluminum-based coating. It tends to increase scratch force and results in blades vibration and even engine jam. To eliminate this problem, a new lightweight epoxy-based abradable seal coating with high bonding strength was developed by an effective and porosity controllable mixing process that distributes spherical pores uniformly in the continuous matrix. A lightweight coating of 63% porosity with a hardness of 33.1(HR15 Y) can be reached when the content of hollow microspheres is 31 wt.%. The coating density is 0.5 g/cm3 and the bonding strength is as high as 18 MPa.The performance of the epoxy-based coating is comprehensively better than aluminum-based coatings in five essential indices. This study is expected to provide a new technical path for obtaining high-quality abradable seal coatings to guarantee the efficient and safe operation of compressors.展开更多
Background:Hydrogen bonding interaction was considered to play a critical role in controlling drug release from transdermal patch.However,the quantitative evaluation of hydrogen bonding strength between drug and polar...Background:Hydrogen bonding interaction was considered to play a critical role in controlling drug release from transdermal patch.However,the quantitative evaluation of hydrogen bonding strength between drug and polar functional group was rarely reported,and the relationship between hydrogen bonding strength and controlled release capacity of pressure sensitive adhesive(PSA)was not well understood.The present study shed light on this relationship.Methods:Acrylate PSAs with amide group were synthesized by a free radical-initiated solution polymerization.Six drugs,i.e.,etodolac,ketoprofen,gemfibrozil,zolmitriptan,propranolol and lidocaine,were selected as model drugs.In vitro drug release and skin permeation experiments and in vivo pharmacokinetic experiment were performed.Partial correlation analysis,fourier-transform infrared spectroscopy and molecular simulation were conducted to provide molecular details of drug-PSA interactions.Mechanical test,rheology study,and modulated differential scanning calorimetry study were performed to scrutinize the free volume and molecular mobility of PSAs.Results:Release rate of all six drugs from amide PSAs decreased with the increase of amide group concentrations;however,only zolmitriptan and propranolol showed decreased skin permeation rate.It was found that drug release was controlled by amide group through hydrogen bonding,and controlled release extent was positively correlated with hydrogen bonding strength.Conclusion:From these results,we concluded that drugs with strong hydrogen bond forming ability and high skin permeation were suitable to use amide PSAs to regulate their release rate from patch.展开更多
In this paper,by proposing a novel and low-cost Ag salt paste,a robustly and large-area(35×35 mm^(2))bare Cu to Cu bonding was realized under a low sintering pressure of 0.8 MPa and a low sintering temperature of...In this paper,by proposing a novel and low-cost Ag salt paste,a robustly and large-area(35×35 mm^(2))bare Cu to Cu bonding was realized under a low sintering pressure of 0.8 MPa and a low sintering temperature of 300℃ in air atmospheric conditions.The relationship between the bonding strength and microstructure changes of sintered Ag under various bonding conditions was investigated in detail.The large-area bonded plate exhibits low porosity about 10%and low percentage of voids,which result in ultra-high bonding strength over 58 MPa.More importantly,the introduction of reducing agent formic acid(CH_(2)O_(2))and the low porosity successfully improve the anti-oxidation of novel Ag salt paste during sintering process,result in pure Cu-Ag-Cu bonding.The cross-section of the Ag joints was obtained to explain the bonding pattern,in which Cu was oxidized only at the edge of the sintering interface,and no Cu oxide generated in middle bonding section.The development of novel Ag salt paste successfully addresses the energy-intensive process and low bonding strength faced by large-scale sintering,which greatly promotes the high-temperature applications of power device.展开更多
Factors influencing bonding strength of laminated bamboo strips lumber (LBSL) were investigated in this paper. In order to find an optimized technology, this paper investigated how the thickness of bamboo strips, the ...Factors influencing bonding strength of laminated bamboo strips lumber (LBSL) were investigated in this paper. In order to find an optimized technology, this paper investigated how the thickness of bamboo strips, the assembly orientation of bamboo curtain, the type of adhesives, as well as coupling agent treatment of bamboo curtain affected the bonding strength. The following conclusions were drawn: 1)The thinner the thickness of the bamboo strips, the bigger the bonding strength of LBSL; 2) The assembly orientation of the bamboo curtain benefited the bonding strength, MOR and MOE; 3) The bonding strength increased with the use of phenol-resorcinol-formaldehyde (PRF) resin; and 4) Treatment of coupling agent could increase the bonding strength but decrease both MOR and MOE.展开更多
Confining stresses serve as a pivotal determinant in shaping the behavior of grouted rock bolts.Nonetheless,prior investigations have oversimplified the three-dimensional stress state,primarily assuming hydrostatic st...Confining stresses serve as a pivotal determinant in shaping the behavior of grouted rock bolts.Nonetheless,prior investigations have oversimplified the three-dimensional stress state,primarily assuming hydrostatic stress conditions.Under these conditions,it is assumed that the intermediate principal stress(σ_(2))equals the minimum principal stress(σ_(3)).This assumption overlooks the potential variations in magnitudes of in situ stress conditions along all three directions near an underground opening where a rock bolt is installed.In this study,a series of push tests was meticulously conducted under triaxial conditions.These tests involved applying non-uniform confining stresses(σ_(2)≠σ_(3))to cubic specimens,aiming to unveil the previously overlooked influence of intermediate principal stresses on the strength properties of rock bolts.The results show that as the confining stresses increase from zero to higher levels,the pre-failure behavior changes from linear to nonlinear forms,resulting in an increase in initial stiffness from 2.08 kN/mm to 32.51 kN/mm.The load-displacement curves further illuminate distinct post-failure behavior at elevated levels of confining stresses,characterized by enhanced stiffness.Notably,the peak load capacity ranged from 27.9 kN to 46.5 kN as confining stresses advanced from σ_(2)=σ_(3)=0 to σ_(2)=20 MPa and σ_(3)=10 MPa.Additionally,the outcomes highlight an influence of confining stress on the lateral deformation of samples.Lower levels of confinement prompt overall dilation in lateral deformation,while higher confinements maintain a state of shrinkage.Furthermore,diverse failure modes have been identified,intricately tied to the arrangement of confining stresses.Lower confinements tend to induce a splitting mode of failure,whereas higher loads bring about a shift towards a pure interfacial shear-off and shear-crushed failure mechanism.展开更多
The concept of resonance-assisted hydrogen bonds(RAHBs)highlights the synergistic interplay between theπ-resonance and hydrogen bonding interactions.This concept has been well-accepted in academia and is widely used ...The concept of resonance-assisted hydrogen bonds(RAHBs)highlights the synergistic interplay between theπ-resonance and hydrogen bonding interactions.This concept has been well-accepted in academia and is widely used in practice.However,it has been argued that the seemingly enhanced intramolecular hydrogen bonding(IMHB)in unsaturated compounds may simply be a result of the constraints imposed by theσ-skeleton framework.Thus,it is crucial to estimate the strength of IMHBs.In this work,we used two approaches to probe the resonance effect and estimate the strength of the IMHBs in the two exemplary cases of the enol forms of acetylacetone and o-hydroxyacetophenone.One approach is the block-localized wavefunction(BLW)method,which is a variant of the ab initio valence bond(VB)theory.Using this approach,it is possible to derive the geometries and energetics with resonance shut down.The other approach is Edmiston’s truncated localized molecular orbital(TLMO)technique,which monitors the energy changes by removing the delocalization tails from localized molecular orbitals.The integrated BLW and TLMO studies confirmed that the hydrogen bonding in these two molecules is indeed enhanced byπ-resonance,and that this enhancement is not a result ofσconstraints.展开更多
This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs)...This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs). The CNT-containing RPC solution with 90 wt% acetone and 10 wt% resin(without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation.Normal epoxy adhesive(resin + hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100%depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.展开更多
Background: To date there is not a material considered ideal for the lased dentin. Objective: To compare the bond strength to human lased dentin of self-etch and etch-and-rinse adhesive systems, a self-adhesive resin ...Background: To date there is not a material considered ideal for the lased dentin. Objective: To compare the bond strength to human lased dentin of self-etch and etch-and-rinse adhesive systems, a self-adhesive resin composite and a glass-ionomer cement. Methods: Forty human molars were sectioned to obtain a 2 mm-thick slab of mid-coronal dentin. The occlusal surface of each slab was polished by SiC paper (P600) for 10 s. Then an half part of dentin slabs was randomly selected for receiving treatment with 2.94 μm Er:YAG laser (DEKA, Smart 2940D Plus) with 10 Hz at 100 mJ, pulse duration of 230 μs with contact tip. Dentin slabs were randomly divided into four groups (n = 10). Six conical frustum-shaped build-ups were constructed on the occlusal surface of each dentin slab using bonding agents (OptiBond Solo Plus Group 1;OptiBond All-in-one Group 2) combined with a resin composite (Premise Flow), self-adhesive resin composites (Vertise Flow Group 3) and a glass-ionomer cement (Ketac-Fil Group 4). Specimens were subjected to μSBS test. Data were analyzed by a mixed model and Tukey’s test. Results: Measured bond strengths were (mean ± standard deviation): 20.8 ± 5.5 MPa (laser treatment) and 15.6 ± 4.5 MPa (SiC paper) for Group 1, 18.9 ± 5.3 MPa (laser treatment) and 14.0 ± 4.3 MPa (SiC paper) for Group 2, 7.9 ± 2.8 MPa (laser treatment) and 4.3 ± 2.2 MPa (SiC paper) for Group 3, 4.7 ± 1.9 MPa (laser treatment) and 2.6 ± 1.2 MPa (SiC paper) for Group 4. The inferential analysis showed that the dentin laser treatment significantly affected the bond strength within each individual group. On dentin treated with laser the bond strengths recorded for build-ups constructed with etch and rinse and self-etch adhesive systems were significantly higher than those recorded for build-ups constructed with self-adhesive resin composite and glass-ionomer cement (p < 0.0001). Similarly, on dentin treated with SiC paper the bond strengths recorded for build-ups constructed with etch and rinse and self-etch adhesive systems were significantly higher than those recorded for build-ups constructed with self-adhesive resin composite and glass-ionomer cement (p < 0.0001). Conclusion: Er:YAG laser treatment has increased the shear bond strength of all the adhesive materials used.展开更多
This study aimed to evaluate the effects of universal primers on the tensile bond strength between zirconia and resin composites.Zirconia specimens were divided into five groups based on the surface treatment with the...This study aimed to evaluate the effects of universal primers on the tensile bond strength between zirconia and resin composites.Zirconia specimens were divided into five groups based on the surface treatment with the following primers:MP(Monobond Plus),SU(ScotchBond Universal),AZ(AZ Primer),BM(Beauty bond Multi),and BL(Bondmer Lightless).After priming,stainless steel rods were bonded to the zirconia specimens with composite resin.The tensile bond strength test was performed:stored at room temperature for 1 day;stored in distilled water at 37°C for 7 days;and underwent thermal cycling.The BL group demonstrated a significantly higher tensile bond strength than other groups when stored at room temperature for 1 day(p<0.05).The primer that acted via chemical polymerization appeared to be most effective in improving the bond strength between the two materials in this study.展开更多
The aim of the study was to investigate the effect of different surface treatment of titanium(Ti)on the adhesion test results for dental application.Ti substrates roughened by 400 to 1500-grit SiC polish papers and al...The aim of the study was to investigate the effect of different surface treatment of titanium(Ti)on the adhesion test results for dental application.Ti substrates roughened by 400 to 1500-grit SiC polish papers and alumina blasting,alkali treated by 5 molar(M)NaOH and KOH solutions and heat treated at the temperature range of 400-800℃were used in this study.The treated samples were subjected to the adhesion test.According to the results of the adhesion test,the adhesive strength showed the highest value for the blasted titanium among all polished and blasted samples.The Ti samples heated at 650℃showed the highest adhesive strength among all heat-treated samples.Further,the adhesion test results indicated the higher adhesive strength of chemically treated samples treated by NaOH rather than that by KOH.The polished and heated Ti samples showed the highest adhesive strength among all samples.展开更多
Nut shells have good impact and fracture resistance,but many kinds of nut shells have suture structures with low bonding strength.Therefore,the mechanism of impact and fracture resistance of nut shells as a whole is i...Nut shells have good impact and fracture resistance,but many kinds of nut shells have suture structures with low bonding strength.Therefore,the mechanism of impact and fracture resistance of nut shells as a whole is important to study,particularly given that sutures maintain low bonding strength.In this study,we investigated the effect of the geometrical characteristics of sutures(morphology,thickness,and number)on the overall fracture resistance of walnuts,based on mechanical tests of C-ring samples,microstructure analysis after cracking,quantitative analysis of suture geometric model,and numerical simulations.We found that the cracking of walnuts was mainly caused by tensile stress,and the bonding strength was approximately 2.48±0.64 MPa.We discovered that the thickness of the suture was 1.55±0.32 times thicker than the shell,which improved the fracture resistance ability by more than 28.4%.The undulating and inclined morphology of the walnut suture also increased the fracture force.Additionally,an appropriate suture number reduced the cracking of walnuts.In conclusion,our study sheds light on the physiological function of walnut sutures from a biomechanical perspective and provides useful references for designing fracture resistance measures in thin shell structures.展开更多
The study characterized the curing behaviors of phenol formaldehyde(PF)resin under different vacuum degrees and explored the properties of 9-ply plywood panels hot-pressed under both vacuum and atmospheric conditions....The study characterized the curing behaviors of phenol formaldehyde(PF)resin under different vacuum degrees and explored the properties of 9-ply plywood panels hot-pressed under both vacuum and atmospheric conditions.The changes in core temperature and moisture content of the plywood mats during hot pressing were investigated as well.It was found that the gel times and gel temperatures of PF resin decreased with the increase of vacuum degree using a self-made device.FTIR spectra indicated the degree of polycondensation of hydroxymethyl gradu-ally increased with the increase in temperature.It was also observed that a higher degree of vacuum led to a slower polycondensation reaction rate of PF resin.During different hot-pressing processes,the bonding strengths in the innermost and uppermost gluelines of the vacuum hot-pressed plywood panels were up to 30%–50%higher than their counterparts of conventional hot-pressed products.A less difference in the bonding strengths between these two gluelines was also observed for vacuum hot-pressed products.In addition,the core of vacuum hot-pressed plywood was found to have a greater heating rate and higher temperature at thefinal stage of hot pressing,which was beneficial to cure the PF resin.The results from this study indicate a promising potential of introducing a vacuum during hot pressing to improve the quality and productivity of plywood products and provide a basis for adopting vacuum to hot press wood composites.展开更多
The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength(SBS)of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multipl...The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength(SBS)of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multiple comparison tests after etching with 35% H_(3)PO_(4). SBS and marginal microleakage tests were conducted with Single Bond Universal(SBU)/Single Bond 2(SB2) adhesives with or without pre-etching using a nonparametric Kruskal-Wallis test. Clinical investigations were performed to validate the adhesive for primary teeth restoration using Chi-square tests. Results showed that the SBS and length of resin protrusion increased significantly with the etching time. Teeth in the SBU with 35% H_(3)PO_(4)pre-etching groups had higher bond strength and lower marginal microleakage than those in the SB2 groups. Mixed fractures were more common in the 35% H_(3)PO_(4)etched 30 s + SB2/SBU groups. Clinical investigations showed significant differences between the two groups in cumulative retention rates at the 6-, 12-and 18-month follow-up evaluations, as well as in marginal adaptation, discoloration, and secondary caries at the 12-and 18-month follow-up assessments.Together, pre-etching primary teeth enamel for 30 s before SBU treatment improved clinical composite resin restoration, which can provide a suitable approach for restoration of primary teeth.展开更多
Rock anchors are a common safety measure for stabilising large-scale infrastructure,such as bridge towers,retaining walls,rock slopes and windmills.There are four principal failure modes for rock anchors:(a)tensile fa...Rock anchors are a common safety measure for stabilising large-scale infrastructure,such as bridge towers,retaining walls,rock slopes and windmills.There are four principal failure modes for rock anchors:(a)tensile failure of the steel anchor,(b)anchor-grout interface failure,(c)grout-rock interface failure,and(d)rock mass uplift.Field tests were performed in a limestone quarry.These tests were designed to test failure modes B and C through pullout.In the tests of failure mode B,the shear stress on the anchor-grout interface is the largest at the top of the grout column and attenuates towards the distal end for small loads.The shear stress becomes uniformly distributed when the applied load is approximately 50%of the ultimate pullout load.The anchors designed to test failure mode C were installed with an endplate and had a higher toughness than the straight bar anchors.The shear stress on the grout-rock interface is the largest at the endplate and attenuates upward before slip starts along the interface.When the ultimate pullout load is reached,and the grout column starts to slip,the shear stress is approximately constant.The bond shear strength on the anchor-grout interface was approximately 20%of the uniaxial compressive strength of the grout,and the bond strength of the grout-rock interface was around 5%for that of the grout.The grout-rock interface is likely determined by whichever is weaker,the grout or the rock.展开更多
Superhydrophobic coatings have been considerably used in corrosion and its protection of metallic Mg.And the comprehensive performance(hydrophobicity,bonding strength,and corrosion resistance,etc.)of the top coating m...Superhydrophobic coatings have been considerably used in corrosion and its protection of metallic Mg.And the comprehensive performance(hydrophobicity,bonding strength,and corrosion resistance,etc.)of the top coating may be highly dependent on the physical and chemical properties of the primer or under coat.Herein,an integrated superhydrophobic polypropylene(PP)coating was fabricated on the micro-arc oxidized Mg substrate via one-step dipping.Surface morphologies and chemical compositions of the composite coating were examined through Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),and field-emission scanning electron microscopy(FESEM)together with X-ray photoelectron spectroscopy(XPS).The surface wettability of the coating was determined by contact angle and sliding angle.The corrosion-resistant performance was evaluated via electrochemical and immersion measurements.The results showed that the hybrid coating possessed micron-scaled granular structure on the surface with a high water contact angle of 167.2±0.8°and a low water sliding angle of 2.7±0.5°.The corrosion resistance of superhydrophobic coating was obviously enhanced with a low corrosion current density of 8.76×10^(−9)A/cm^(2),and the coating still maintained integrity after 248 h of immersion in 3.5wt%NaCl aqueous solution.The MAO coating provides better adhesion of PP to the surface.Hence,the superhydrophobic coating exhibited superior bonding strength,corrosion resistance and durability.展开更多
基金sponsored by the MOEA(Ministry of Economic Affairs)from the Technology Development Program No.109-EC-17-A-25-1581。
文摘In this paper,two types of copper-aluminum heterogeneous electrode plates are stacked and the finite element analysis(FEA)models of two different laser welding conditions are built by using SYSWELD welding simulation software to calculate the depth of the welding bead and the temperature distribution of the welding surface.Then,the residual stress analysis data of the welded area are exported and the residual stress is applied to the welded specimen for CAE analysis to ensure that the welding bonding strength meets the design target of a shear force of 500 N or higher.The copper-aluminum laser-stacking simulation technique in this paper can be applied to the manufacturing of copper-aluminum heterogeneous laser-welded electrodes and series-connected electrodes of automotive lithium-ion power battery modules,providing an effective analysis method for welding bonding-strength.
基金This work was financially supported by the National Nature Science Foundation of China(Grant No.61673222)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.23KJB430036)Wuxi University Research Start-up Fund for Introduced Talents(Grant No.2022r036).
文摘High-quality bonding of 4-inch GaAs and Si is achieved using plasma-activated bonding technology.The influence of Ar plasma activation on surface morphology is discussed.When the annealing temperature is 300℃,the bonding strength reaches a maximum of 6.2 MPa.In addition,a thermal stress model for GaAs/Si wafers is established based on finite element analysis to obtain the distribution of equivalent stress and deformation variables at different temperatures.The shape varia-tion of the wafer is directly proportional to the annealing temperature.At an annealing temperature of 400℃,the maximum protrusion of 4 inches GaAs/Si wafers is 3.6 mm.The interface of GaAs/Si wafers is observed to be dense and defect-free using a transmission electron microscope.The characterization of interface elements by X-ray energy dispersion spectroscopy indi-cates that the elements at the interface undergo mutual diffusion,which is beneficial for improving the bonding strength of the interface.There is an amorphous transition layer with a thickness of about 5 nm at the bonding interface.The preparation of Si-based GaAs heterojunctions can enrich the types of materials required for the development of integrated circuits,improve the performance of materials and devices,and promote the development of microelectronics technology.
文摘The objective of this experimental study is to improve the cementing bond quality of sandstone oil-gas well along the wellbore cement-formation interface(WCFI),so as to ensure long-term zonal isolation throughout the lifecycle of the well by using NsO solution as filtercake modifier which was developed in the laboratory.According to designed experimental method and API RP 10,the effectiveness of filtercake modifier(NSO)on the bonding strength at the WCFI was assessed by using designed simulated wellbore as sandstone formation.The experimental results indicated that the samples which were treated with NsO solution had higher bond strength over untreated samples.The strength generally increased with curing period as for treated samples,0.198,0.374,0.433 and 0.473 MPa for 3,7,15,and 30 days respectively while for the untreated samples the bond strength were 0.050,0.070,0.81 and 0.100 MPa for the same period.The water-based filtercake modification techniques had significantly enhanced the bonding strength of WCFI by increasing rates above 296%.Improvement of bond strength to the treated sample was due to filtercake modification as a result of formation of cementitious material as revealed in FTIR spectral such as Calcium-Silicate-Hydrate(C-S-H)and other geopolymers like Calcium-Aluminium-Silicate-Hydrate(C-A-S-H)and Sodium-Aluminium-Silicate-Hydrate(N-A-S-H)along the interface which filled the existed pores hence reducing porosity hence high strength of bond.The low transmittance value for the NsO treated samples revealed that there were more cementitious materials existing at the WCFI which led to improvement of bonding strength as compared to the untreated samples.The lower/poor bond strength for the untreated samples is due to existence of untreated,thick water-based filtercake films at WCFI,which prevented the complete hydration process between rock grains and cement slurry components to make chemical binder of cement slurry material and formation.2022 The Authors.Publishing services provided by Elsevier B.V.on behalf of KeAi Communication Co.Ltd.This is an open access article under the cc BY license(http://creativecommons.org/licenses/by/4.o/).
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110542)the Guangdong Special Support Program(No.2019BT02C629)+5 种基金the National Natural Science Foundation of China(Nos.52005189and 51775196)the Chinese Postdoctoral Science Foundation(No.2020M672617)the Guangzhou Science and Technology Society Project(Nos.X20200301015,201907010008,202007020008and 201807010030)the Chinese Central Universities Funds(No.2018ZD30)supported by Guangdong province Science and Technology Plan Projects(No.2019A1515011841)GDAS Projects(Nos.2020GDASYL-20200402005,2019GDASYL-0501009,2019GDASYL-0502006,2018GDASCX-0111,2018GDASCX-0402 and 2019GDASYL-0402004)。
文摘Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder bed fusion(LPBF).The effect of laser process parameters on interfacial defects was evaluated by X-ray tomography,which indicates a low porosity level of 0.042%therein.Gradient/fine dendritic grains in the interface are incited by high cooling rates,which facilitates interface strengthening.Multiple mechanical tests evaluate the bonding reliability of interface;and the fatigue tests further substantiate the ultrahigh bonding strength in FGMs,which is superior to traditional manufacturing methods.Mechanisms of the high interfacial bond strength were also discussed.
基金the National Science and Technology Major Project(No.2017-VII-0012-0107)the National Program for Support of Top-notch Young Professionals。
文摘To gain high efficiency and low fuel consumption, aluminum-based abradable seal coatings had been widely used in the compressor casing of aero engines or gas turbines owing to the low elastic modulus. However, the adhesive transfer phenomenon frequently occurs when the radial rubbing generates between titanium alloy blade tips and aluminum-based coating. It tends to increase scratch force and results in blades vibration and even engine jam. To eliminate this problem, a new lightweight epoxy-based abradable seal coating with high bonding strength was developed by an effective and porosity controllable mixing process that distributes spherical pores uniformly in the continuous matrix. A lightweight coating of 63% porosity with a hardness of 33.1(HR15 Y) can be reached when the content of hollow microspheres is 31 wt.%. The coating density is 0.5 g/cm3 and the bonding strength is as high as 18 MPa.The performance of the epoxy-based coating is comprehensively better than aluminum-based coatings in five essential indices. This study is expected to provide a new technical path for obtaining high-quality abradable seal coatings to guarantee the efficient and safe operation of compressors.
基金supported by the National Natural Science Foundation of China(81773665)Natural Science Foundation of Liaoning Province(20170540861,China)
文摘Background:Hydrogen bonding interaction was considered to play a critical role in controlling drug release from transdermal patch.However,the quantitative evaluation of hydrogen bonding strength between drug and polar functional group was rarely reported,and the relationship between hydrogen bonding strength and controlled release capacity of pressure sensitive adhesive(PSA)was not well understood.The present study shed light on this relationship.Methods:Acrylate PSAs with amide group were synthesized by a free radical-initiated solution polymerization.Six drugs,i.e.,etodolac,ketoprofen,gemfibrozil,zolmitriptan,propranolol and lidocaine,were selected as model drugs.In vitro drug release and skin permeation experiments and in vivo pharmacokinetic experiment were performed.Partial correlation analysis,fourier-transform infrared spectroscopy and molecular simulation were conducted to provide molecular details of drug-PSA interactions.Mechanical test,rheology study,and modulated differential scanning calorimetry study were performed to scrutinize the free volume and molecular mobility of PSAs.Results:Release rate of all six drugs from amide PSAs decreased with the increase of amide group concentrations;however,only zolmitriptan and propranolol showed decreased skin permeation rate.It was found that drug release was controlled by amide group through hydrogen bonding,and controlled release extent was positively correlated with hydrogen bonding strength.Conclusion:From these results,we concluded that drugs with strong hydrogen bond forming ability and high skin permeation were suitable to use amide PSAs to regulate their release rate from patch.
基金partly supported a project (JPNP14004) commissioned by the New Energy and Industrial Technology Development Organization (NEDO)the supporting from TOPPAN FORMS CO.,LTD,Japan
文摘In this paper,by proposing a novel and low-cost Ag salt paste,a robustly and large-area(35×35 mm^(2))bare Cu to Cu bonding was realized under a low sintering pressure of 0.8 MPa and a low sintering temperature of 300℃ in air atmospheric conditions.The relationship between the bonding strength and microstructure changes of sintered Ag under various bonding conditions was investigated in detail.The large-area bonded plate exhibits low porosity about 10%and low percentage of voids,which result in ultra-high bonding strength over 58 MPa.More importantly,the introduction of reducing agent formic acid(CH_(2)O_(2))and the low porosity successfully improve the anti-oxidation of novel Ag salt paste during sintering process,result in pure Cu-Ag-Cu bonding.The cross-section of the Ag joints was obtained to explain the bonding pattern,in which Cu was oxidized only at the edge of the sintering interface,and no Cu oxide generated in middle bonding section.The development of novel Ag salt paste successfully addresses the energy-intensive process and low bonding strength faced by large-scale sintering,which greatly promotes the high-temperature applications of power device.
基金supported by the national Key Project of Scientific and Technical Supporting Programs of China (No.2006BAD19B0503)
文摘Factors influencing bonding strength of laminated bamboo strips lumber (LBSL) were investigated in this paper. In order to find an optimized technology, this paper investigated how the thickness of bamboo strips, the assembly orientation of bamboo curtain, the type of adhesives, as well as coupling agent treatment of bamboo curtain affected the bonding strength. The following conclusions were drawn: 1)The thinner the thickness of the bamboo strips, the bigger the bonding strength of LBSL; 2) The assembly orientation of the bamboo curtain benefited the bonding strength, MOR and MOE; 3) The bonding strength increased with the use of phenol-resorcinol-formaldehyde (PRF) resin; and 4) Treatment of coupling agent could increase the bonding strength but decrease both MOR and MOE.
文摘Confining stresses serve as a pivotal determinant in shaping the behavior of grouted rock bolts.Nonetheless,prior investigations have oversimplified the three-dimensional stress state,primarily assuming hydrostatic stress conditions.Under these conditions,it is assumed that the intermediate principal stress(σ_(2))equals the minimum principal stress(σ_(3)).This assumption overlooks the potential variations in magnitudes of in situ stress conditions along all three directions near an underground opening where a rock bolt is installed.In this study,a series of push tests was meticulously conducted under triaxial conditions.These tests involved applying non-uniform confining stresses(σ_(2)≠σ_(3))to cubic specimens,aiming to unveil the previously overlooked influence of intermediate principal stresses on the strength properties of rock bolts.The results show that as the confining stresses increase from zero to higher levels,the pre-failure behavior changes from linear to nonlinear forms,resulting in an increase in initial stiffness from 2.08 kN/mm to 32.51 kN/mm.The load-displacement curves further illuminate distinct post-failure behavior at elevated levels of confining stresses,characterized by enhanced stiffness.Notably,the peak load capacity ranged from 27.9 kN to 46.5 kN as confining stresses advanced from σ_(2)=σ_(3)=0 to σ_(2)=20 MPa and σ_(3)=10 MPa.Additionally,the outcomes highlight an influence of confining stress on the lateral deformation of samples.Lower levels of confinement prompt overall dilation in lateral deformation,while higher confinements maintain a state of shrinkage.Furthermore,diverse failure modes have been identified,intricately tied to the arrangement of confining stresses.Lower confinements tend to induce a splitting mode of failure,whereas higher loads bring about a shift towards a pure interfacial shear-off and shear-crushed failure mechanism.
文摘The concept of resonance-assisted hydrogen bonds(RAHBs)highlights the synergistic interplay between theπ-resonance and hydrogen bonding interactions.This concept has been well-accepted in academia and is widely used in practice.However,it has been argued that the seemingly enhanced intramolecular hydrogen bonding(IMHB)in unsaturated compounds may simply be a result of the constraints imposed by theσ-skeleton framework.Thus,it is crucial to estimate the strength of IMHBs.In this work,we used two approaches to probe the resonance effect and estimate the strength of the IMHBs in the two exemplary cases of the enol forms of acetylacetone and o-hydroxyacetophenone.One approach is the block-localized wavefunction(BLW)method,which is a variant of the ab initio valence bond(VB)theory.Using this approach,it is possible to derive the geometries and energetics with resonance shut down.The other approach is Edmiston’s truncated localized molecular orbital(TLMO)technique,which monitors the energy changes by removing the delocalization tails from localized molecular orbitals.The integrated BLW and TLMO studies confirmed that the hydrogen bonding in these two molecules is indeed enhanced byπ-resonance,and that this enhancement is not a result ofσconstraints.
基金Chang’an University of China for a visiting professor grant (2018-2020) for research collaboration between Chang’an University and University of Western Australia。
文摘This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs). The CNT-containing RPC solution with 90 wt% acetone and 10 wt% resin(without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation.Normal epoxy adhesive(resin + hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100%depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.
文摘Background: To date there is not a material considered ideal for the lased dentin. Objective: To compare the bond strength to human lased dentin of self-etch and etch-and-rinse adhesive systems, a self-adhesive resin composite and a glass-ionomer cement. Methods: Forty human molars were sectioned to obtain a 2 mm-thick slab of mid-coronal dentin. The occlusal surface of each slab was polished by SiC paper (P600) for 10 s. Then an half part of dentin slabs was randomly selected for receiving treatment with 2.94 μm Er:YAG laser (DEKA, Smart 2940D Plus) with 10 Hz at 100 mJ, pulse duration of 230 μs with contact tip. Dentin slabs were randomly divided into four groups (n = 10). Six conical frustum-shaped build-ups were constructed on the occlusal surface of each dentin slab using bonding agents (OptiBond Solo Plus Group 1;OptiBond All-in-one Group 2) combined with a resin composite (Premise Flow), self-adhesive resin composites (Vertise Flow Group 3) and a glass-ionomer cement (Ketac-Fil Group 4). Specimens were subjected to μSBS test. Data were analyzed by a mixed model and Tukey’s test. Results: Measured bond strengths were (mean ± standard deviation): 20.8 ± 5.5 MPa (laser treatment) and 15.6 ± 4.5 MPa (SiC paper) for Group 1, 18.9 ± 5.3 MPa (laser treatment) and 14.0 ± 4.3 MPa (SiC paper) for Group 2, 7.9 ± 2.8 MPa (laser treatment) and 4.3 ± 2.2 MPa (SiC paper) for Group 3, 4.7 ± 1.9 MPa (laser treatment) and 2.6 ± 1.2 MPa (SiC paper) for Group 4. The inferential analysis showed that the dentin laser treatment significantly affected the bond strength within each individual group. On dentin treated with laser the bond strengths recorded for build-ups constructed with etch and rinse and self-etch adhesive systems were significantly higher than those recorded for build-ups constructed with self-adhesive resin composite and glass-ionomer cement (p < 0.0001). Similarly, on dentin treated with SiC paper the bond strengths recorded for build-ups constructed with etch and rinse and self-etch adhesive systems were significantly higher than those recorded for build-ups constructed with self-adhesive resin composite and glass-ionomer cement (p < 0.0001). Conclusion: Er:YAG laser treatment has increased the shear bond strength of all the adhesive materials used.
文摘This study aimed to evaluate the effects of universal primers on the tensile bond strength between zirconia and resin composites.Zirconia specimens were divided into five groups based on the surface treatment with the following primers:MP(Monobond Plus),SU(ScotchBond Universal),AZ(AZ Primer),BM(Beauty bond Multi),and BL(Bondmer Lightless).After priming,stainless steel rods were bonded to the zirconia specimens with composite resin.The tensile bond strength test was performed:stored at room temperature for 1 day;stored in distilled water at 37°C for 7 days;and underwent thermal cycling.The BL group demonstrated a significantly higher tensile bond strength than other groups when stored at room temperature for 1 day(p<0.05).The primer that acted via chemical polymerization appeared to be most effective in improving the bond strength between the two materials in this study.
文摘The aim of the study was to investigate the effect of different surface treatment of titanium(Ti)on the adhesion test results for dental application.Ti substrates roughened by 400 to 1500-grit SiC polish papers and alumina blasting,alkali treated by 5 molar(M)NaOH and KOH solutions and heat treated at the temperature range of 400-800℃were used in this study.The treated samples were subjected to the adhesion test.According to the results of the adhesion test,the adhesive strength showed the highest value for the blasted titanium among all polished and blasted samples.The Ti samples heated at 650℃showed the highest adhesive strength among all heat-treated samples.Further,the adhesion test results indicated the higher adhesive strength of chemically treated samples treated by NaOH rather than that by KOH.The polished and heated Ti samples showed the highest adhesive strength among all samples.
基金This work was supported by the National Natural Science Foundation of China[U2241273,12172034,U20A20390,11827803,11822201]Beijing Municipal Natural Science Foundation[7212205]+1 种基金the 111 project[B13003]the Fundamental Research Funds for the Central Universities.
文摘Nut shells have good impact and fracture resistance,but many kinds of nut shells have suture structures with low bonding strength.Therefore,the mechanism of impact and fracture resistance of nut shells as a whole is important to study,particularly given that sutures maintain low bonding strength.In this study,we investigated the effect of the geometrical characteristics of sutures(morphology,thickness,and number)on the overall fracture resistance of walnuts,based on mechanical tests of C-ring samples,microstructure analysis after cracking,quantitative analysis of suture geometric model,and numerical simulations.We found that the cracking of walnuts was mainly caused by tensile stress,and the bonding strength was approximately 2.48±0.64 MPa.We discovered that the thickness of the suture was 1.55±0.32 times thicker than the shell,which improved the fracture resistance ability by more than 28.4%.The undulating and inclined morphology of the walnut suture also increased the fracture force.Additionally,an appropriate suture number reduced the cracking of walnuts.In conclusion,our study sheds light on the physiological function of walnut sutures from a biomechanical perspective and provides useful references for designing fracture resistance measures in thin shell structures.
文摘The study characterized the curing behaviors of phenol formaldehyde(PF)resin under different vacuum degrees and explored the properties of 9-ply plywood panels hot-pressed under both vacuum and atmospheric conditions.The changes in core temperature and moisture content of the plywood mats during hot pressing were investigated as well.It was found that the gel times and gel temperatures of PF resin decreased with the increase of vacuum degree using a self-made device.FTIR spectra indicated the degree of polycondensation of hydroxymethyl gradu-ally increased with the increase in temperature.It was also observed that a higher degree of vacuum led to a slower polycondensation reaction rate of PF resin.During different hot-pressing processes,the bonding strengths in the innermost and uppermost gluelines of the vacuum hot-pressed plywood panels were up to 30%–50%higher than their counterparts of conventional hot-pressed products.A less difference in the bonding strengths between these two gluelines was also observed for vacuum hot-pressed products.In addition,the core of vacuum hot-pressed plywood was found to have a greater heating rate and higher temperature at thefinal stage of hot pressing,which was beneficial to cure the PF resin.The results from this study indicate a promising potential of introducing a vacuum during hot pressing to improve the quality and productivity of plywood products and provide a basis for adopting vacuum to hot press wood composites.
基金supported by the Technology Development Fund of Nanjing Medical University(Grants No.NMUB2016115 and NMUB2020117)。
文摘The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength(SBS)of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multiple comparison tests after etching with 35% H_(3)PO_(4). SBS and marginal microleakage tests were conducted with Single Bond Universal(SBU)/Single Bond 2(SB2) adhesives with or without pre-etching using a nonparametric Kruskal-Wallis test. Clinical investigations were performed to validate the adhesive for primary teeth restoration using Chi-square tests. Results showed that the SBS and length of resin protrusion increased significantly with the etching time. Teeth in the SBU with 35% H_(3)PO_(4)pre-etching groups had higher bond strength and lower marginal microleakage than those in the SB2 groups. Mixed fractures were more common in the 35% H_(3)PO_(4)etched 30 s + SB2/SBU groups. Clinical investigations showed significant differences between the two groups in cumulative retention rates at the 6-, 12-and 18-month follow-up evaluations, as well as in marginal adaptation, discoloration, and secondary caries at the 12-and 18-month follow-up assessments.Together, pre-etching primary teeth enamel for 30 s before SBU treatment improved clinical composite resin restoration, which can provide a suitable approach for restoration of primary teeth.
文摘Rock anchors are a common safety measure for stabilising large-scale infrastructure,such as bridge towers,retaining walls,rock slopes and windmills.There are four principal failure modes for rock anchors:(a)tensile failure of the steel anchor,(b)anchor-grout interface failure,(c)grout-rock interface failure,and(d)rock mass uplift.Field tests were performed in a limestone quarry.These tests were designed to test failure modes B and C through pullout.In the tests of failure mode B,the shear stress on the anchor-grout interface is the largest at the top of the grout column and attenuates towards the distal end for small loads.The shear stress becomes uniformly distributed when the applied load is approximately 50%of the ultimate pullout load.The anchors designed to test failure mode C were installed with an endplate and had a higher toughness than the straight bar anchors.The shear stress on the grout-rock interface is the largest at the endplate and attenuates upward before slip starts along the interface.When the ultimate pullout load is reached,and the grout column starts to slip,the shear stress is approximately constant.The bond shear strength on the anchor-grout interface was approximately 20%of the uniaxial compressive strength of the grout,and the bond strength of the grout-rock interface was around 5%for that of the grout.The grout-rock interface is likely determined by whichever is weaker,the grout or the rock.
基金This work was supported by the National Natural Science Foundation of China(51571134)the SDUST Research Fund(2014TDJH104).
文摘Superhydrophobic coatings have been considerably used in corrosion and its protection of metallic Mg.And the comprehensive performance(hydrophobicity,bonding strength,and corrosion resistance,etc.)of the top coating may be highly dependent on the physical and chemical properties of the primer or under coat.Herein,an integrated superhydrophobic polypropylene(PP)coating was fabricated on the micro-arc oxidized Mg substrate via one-step dipping.Surface morphologies and chemical compositions of the composite coating were examined through Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),and field-emission scanning electron microscopy(FESEM)together with X-ray photoelectron spectroscopy(XPS).The surface wettability of the coating was determined by contact angle and sliding angle.The corrosion-resistant performance was evaluated via electrochemical and immersion measurements.The results showed that the hybrid coating possessed micron-scaled granular structure on the surface with a high water contact angle of 167.2±0.8°and a low water sliding angle of 2.7±0.5°.The corrosion resistance of superhydrophobic coating was obviously enhanced with a low corrosion current density of 8.76×10^(−9)A/cm^(2),and the coating still maintained integrity after 248 h of immersion in 3.5wt%NaCl aqueous solution.The MAO coating provides better adhesion of PP to the surface.Hence,the superhydrophobic coating exhibited superior bonding strength,corrosion resistance and durability.
