The adhesion between the ion plated TiN coating and the base metal is improved by adding Y.The machenism of the effect of Y has been discussed as well.
The effect of rare earth(RE) additives on the quality of brush plated coating was studied by adding RE into brush plating solution. The results show that RE make the surface smooth and shiny, reduce residual stress ...The effect of rare earth(RE) additives on the quality of brush plated coating was studied by adding RE into brush plating solution. The results show that RE make the surface smooth and shiny, reduce residual stress within the coating and reinforced bond, and increase the wearability and corrosion resistance.展开更多
Banana streak virus (BSV) and Sugarcane bacilliform virus (SCBV) are two badnaviruses commonly found in all banana growing areas of the world. It is a threat to the production and improvement of Musa germplasm. In Bur...Banana streak virus (BSV) and Sugarcane bacilliform virus (SCBV) are two badnaviruses commonly found in all banana growing areas of the world. It is a threat to the production and improvement of Musa germplasm. In Burkina Faso, the presence of badnaviruses was reported in banana producing regions. The objective of this study was to determine the prevalence of BSV and SCBV in banana production areas of Burkina Faso. A survey followed by a symptomatologic study was conducted in banana plantations in 27 localities of the nine main banana producing regions from July to October 2018 and September to December 2020. In all, 251 leaf samples were collected and analysed for BSV and SCBV infection by Indirect Antigen Coated Plate Assay-ELISA followed by amplification of the RT/RNase H region using Polymerase chain reaction with Badna FP/RP and SCBV F/R primers, respectively. A variety of symptoms were observed on almost all plant organs which were revealed due to BSV by symptomatologic study. The results of serological and molecular diagnosis revealed a high overall prevalence of BSV in 80.48% of the samples tested. BSV was distributed in seven survey regions out of nine with prevalence ranging from 10% to 100% in North, Centre, Centre West, Hauts Bassins, Cascades, Centre East and Boucle of Mouhoun regions. Very low prevalence was recorded for SCBV in Cascades and East Centre region with 4.35 and 12.5%, respectively. Species detection using specific primers to each species revealed three main species: Banana streak Obino l’ewaï virus (BSOLV), Goldfinger virus (BSGFV) and Imové virus (BSIMV) in the samples tested, respectively in the proportions of 23%, 8% and 0.8%. Co-infection between BSV species was also detected.展开更多
Technology and properties of electroless composite RE-Ni-B-SiC coatings have been investigated.Results show that stabilizer plys a decisive role in electroless composite Ni-B-SiC,the addition of appropriate quantity o...Technology and properties of electroless composite RE-Ni-B-SiC coatings have been investigated.Results show that stabilizer plys a decisive role in electroless composite Ni-B-SiC,the addition of appropriate quantity of RE(rare earth) into the Ni-B-SiC bath not only increases SiC content in composite coatings,their hardness and wear resistance but also improves crystalline fineness,Wear resistance increases with the increase of SiC.Hardness and wear resistance of composite coatings reach peak values a fter heat treatment at 4OO and 500℃ for 1h respectively.展开更多
To predict sound-absorbing performance of anechoic materials,the acoustic reflection problem of a viscoelastic layer backed with periodically rib-stiffened infinite double plates is studied in this paper.The reason wh...To predict sound-absorbing performance of anechoic materials,the acoustic reflection problem of a viscoelastic layer backed with periodically rib-stiffened infinite double plates is studied in this paper.The reason why structural theories of plates are not applicable to viscoelastic plates is explained through comparing dispersion and attenuation curves of flexural waves with those of Lamb waves.As a result,（visco-）elastic theory is adopted to deal with（visco-）elastic plates,and ribs are treated by structural theories of plates.The coupling between ribs and plates are solved by Hull＇s method,and solution of the reflected field is obtained.The accuracy of present method is validated by comparing with the results by the structural theories of plates.The influence of a backing on the acoustic reflection of the viscoelatic layer is analyzed by computing reflection coefficients.Performances of different viscoelastic materials are evaluated by the average reflection coefficients.The computational results show that,influence of a backing on the acoustic reflection cannot be suppressed by the viscoelastic materials in low frequencies.The resonance is determined by the coupling of the fluid layer and the double plates.And ribs,which are coupled with the double plates,mainly reduce the acoustic reflection.展开更多
The effect of four kinds of rare earth elements on the depositing rate of Ni-based alloy brush plating coatings was investigated. The results indicate that all of the selected rare earth elements increase the depositi...The effect of four kinds of rare earth elements on the depositing rate of Ni-based alloy brush plating coatings was investigated. The results indicate that all of the selected rare earth elements increase the depositing rate of Ni-based alloy coatings, and Sm increases the depositing rate most obviously. There is an optimum amount of rare earth addition in the plating solution. With the change of plating voltage to a certain extent, the results reveal no differences. The mechanism of the increase of the depositing rate was analyzed.展开更多
A modified ion-plated TiN(IP-TiN) coating has been developed by adding 6 wt-% A1 and small amounts of La.Examination of this coating showed that the adhesion between the coat- ing and substrate is remarkably improved ...A modified ion-plated TiN(IP-TiN) coating has been developed by adding 6 wt-% A1 and small amounts of La.Examination of this coating showed that the adhesion between the coat- ing and substrate is remarkably improved by the La added up to 2 wt-% ,and the microhardness and wear resistance of the coating surface closely relate to the contents of La.EPMA and X-ray diffraction analysis indicated that a thick transition zone forms owing to the addition of La and A1.The phase composition and grain orientation of the coating change because of the formation of such transition zone.Thus,the properties of coating were improved.展开更多
In this study, a NiCrAIY ＋ AINiY composite coating was prepared by arc ion plating technique and sub- sequent annealing treatment. Cyclic hot corrosion tests of the composite coating and a reference NiCrAIY coating c...In this study, a NiCrAIY ＋ AINiY composite coating was prepared by arc ion plating technique and sub- sequent annealing treatment. Cyclic hot corrosion tests of the composite coating and a reference NiCrAIY coating coated with mixed salts of Na2SO4 ＋ K2SO4 and Na2SO4 ＋ NaC1 were carried out at 700 ℃. The results indicated that the composite coating performed better against the corrosion due to the gradient element distribution in Al-enriched outer layer and Cr-enriched inner layer. The corrosion mechanisms for the two coatings were also discussed.展开更多
A Cr-modified aluminide coating is prepared on a Ni-based superalloy using arc ion plating and subsequent pack cementation aluminizing.Hot corrosion behavior of the Cr-modified aluminide coating exposed to molten Na2S...A Cr-modified aluminide coating is prepared on a Ni-based superalloy using arc ion plating and subsequent pack cementation aluminizing.Hot corrosion behavior of the Cr-modified aluminide coating exposed to molten Na2SO4/K2SO4（3：1） or Na2SO4/NaCl（3：1） salts at 900 °C in static air are evaluated as well as the aluminide coating.The results indicate that compared with the aluminide coating,the anti-corrosion properties of the Cr-modified aluminide coating in the both salts are improved,which should be attributed to the beneficial effect of the Cr in the coating.The corrosion mechanism of the Cr-modified aluminide coating,especially the role of Cr in the mixture salt corrosion,is discussed.展开更多
文摘The adhesion between the ion plated TiN coating and the base metal is improved by adding Y.The machenism of the effect of Y has been discussed as well.
文摘The effect of rare earth(RE) additives on the quality of brush plated coating was studied by adding RE into brush plating solution. The results show that RE make the surface smooth and shiny, reduce residual stress within the coating and reinforced bond, and increase the wearability and corrosion resistance.
文摘Banana streak virus (BSV) and Sugarcane bacilliform virus (SCBV) are two badnaviruses commonly found in all banana growing areas of the world. It is a threat to the production and improvement of Musa germplasm. In Burkina Faso, the presence of badnaviruses was reported in banana producing regions. The objective of this study was to determine the prevalence of BSV and SCBV in banana production areas of Burkina Faso. A survey followed by a symptomatologic study was conducted in banana plantations in 27 localities of the nine main banana producing regions from July to October 2018 and September to December 2020. In all, 251 leaf samples were collected and analysed for BSV and SCBV infection by Indirect Antigen Coated Plate Assay-ELISA followed by amplification of the RT/RNase H region using Polymerase chain reaction with Badna FP/RP and SCBV F/R primers, respectively. A variety of symptoms were observed on almost all plant organs which were revealed due to BSV by symptomatologic study. The results of serological and molecular diagnosis revealed a high overall prevalence of BSV in 80.48% of the samples tested. BSV was distributed in seven survey regions out of nine with prevalence ranging from 10% to 100% in North, Centre, Centre West, Hauts Bassins, Cascades, Centre East and Boucle of Mouhoun regions. Very low prevalence was recorded for SCBV in Cascades and East Centre region with 4.35 and 12.5%, respectively. Species detection using specific primers to each species revealed three main species: Banana streak Obino l’ewaï virus (BSOLV), Goldfinger virus (BSGFV) and Imové virus (BSIMV) in the samples tested, respectively in the proportions of 23%, 8% and 0.8%. Co-infection between BSV species was also detected.
文摘Technology and properties of electroless composite RE-Ni-B-SiC coatings have been investigated.Results show that stabilizer plys a decisive role in electroless composite Ni-B-SiC,the addition of appropriate quantity of RE(rare earth) into the Ni-B-SiC bath not only increases SiC content in composite coatings,their hardness and wear resistance but also improves crystalline fineness,Wear resistance increases with the increase of SiC.Hardness and wear resistance of composite coatings reach peak values a fter heat treatment at 4OO and 500℃ for 1h respectively.
基金supported by the Research Funds(9140A10040813CB04001)the Natural Science Foundation of Shandong Province(2013ZRF01039)
文摘To predict sound-absorbing performance of anechoic materials,the acoustic reflection problem of a viscoelastic layer backed with periodically rib-stiffened infinite double plates is studied in this paper.The reason why structural theories of plates are not applicable to viscoelastic plates is explained through comparing dispersion and attenuation curves of flexural waves with those of Lamb waves.As a result,（visco-）elastic theory is adopted to deal with（visco-）elastic plates,and ribs are treated by structural theories of plates.The coupling between ribs and plates are solved by Hull＇s method,and solution of the reflected field is obtained.The accuracy of present method is validated by comparing with the results by the structural theories of plates.The influence of a backing on the acoustic reflection of the viscoelatic layer is analyzed by computing reflection coefficients.Performances of different viscoelastic materials are evaluated by the average reflection coefficients.The computational results show that,influence of a backing on the acoustic reflection cannot be suppressed by the viscoelastic materials in low frequencies.The resonance is determined by the coupling of the fluid layer and the double plates.And ribs,which are coupled with the double plates,mainly reduce the acoustic reflection.
文摘The effect of four kinds of rare earth elements on the depositing rate of Ni-based alloy brush plating coatings was investigated. The results indicate that all of the selected rare earth elements increase the depositing rate of Ni-based alloy coatings, and Sm increases the depositing rate most obviously. There is an optimum amount of rare earth addition in the plating solution. With the change of plating voltage to a certain extent, the results reveal no differences. The mechanism of the increase of the depositing rate was analyzed.
文摘A modified ion-plated TiN(IP-TiN) coating has been developed by adding 6 wt-% A1 and small amounts of La.Examination of this coating showed that the adhesion between the coat- ing and substrate is remarkably improved by the La added up to 2 wt-% ,and the microhardness and wear resistance of the coating surface closely relate to the contents of La.EPMA and X-ray diffraction analysis indicated that a thick transition zone forms owing to the addition of La and A1.The phase composition and grain orientation of the coating change because of the formation of such transition zone.Thus,the properties of coating were improved.
基金supported by the National Natural Science Foundation of China(Grant No.51001106)
文摘In this study, a NiCrAIY ＋ AINiY composite coating was prepared by arc ion plating technique and sub- sequent annealing treatment. Cyclic hot corrosion tests of the composite coating and a reference NiCrAIY coating coated with mixed salts of Na2SO4 ＋ K2SO4 and Na2SO4 ＋ NaC1 were carried out at 700 ℃. The results indicated that the composite coating performed better against the corrosion due to the gradient element distribution in Al-enriched outer layer and Cr-enriched inner layer. The corrosion mechanisms for the two coatings were also discussed.
基金financially supported by the National Natural Science Foundation of China (No.51001106)National Basic Research Program of China (No.2012CB625100)
文摘A Cr-modified aluminide coating is prepared on a Ni-based superalloy using arc ion plating and subsequent pack cementation aluminizing.Hot corrosion behavior of the Cr-modified aluminide coating exposed to molten Na2SO4/K2SO4（3：1） or Na2SO4/NaCl（3：1） salts at 900 °C in static air are evaluated as well as the aluminide coating.The results indicate that compared with the aluminide coating,the anti-corrosion properties of the Cr-modified aluminide coating in the both salts are improved,which should be attributed to the beneficial effect of the Cr in the coating.The corrosion mechanism of the Cr-modified aluminide coating,especially the role of Cr in the mixture salt corrosion,is discussed.
