The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-c...The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-coated layer on the binding structure and surface qual- ity of the coating were systematically investigated. The macrostructure, phase composition, and bonding interface between the coating and the substrate were investigated by scanning electronic microscopy （SEM）, X-ray diffraction （XRD）, and energy-dispersive X-ray spectrometry （EDS）. The diffraction patterns indicated that the coating essentially consisted of α-Al2O3, Fe（Cr）, and FeO-Al2O3. With an increase in the thickness of the pre-coated working layer, the coating became more smooth and compact. The transition layer played an important role in enhancing the binding between the coating and the substmte. When the pre-coated working layer was 10 mm and the pre-coated transition layer was 1 ram, a compact structure and metallurgical bonding with the substrate were obtained. Thermal shock test results indicated that the ceramic coating exhibited good thermal shock resistance when the sample was rapidly quenched from 800℃ to room temperature by plunging into water.展开更多
Al2O3-metal composite coatings with different reactants and diluents were fabricated on mild steel plate with nonpressure combustion synthesis process. The coat-ings were characterized by means of X-ray diffraction, s...Al2O3-metal composite coatings with different reactants and diluents were fabricated on mild steel plate with nonpressure combustion synthesis process. The coat-ings were characterized by means of X-ray diffraction, scanning electron microscopy, and energy-dispersive spec-trometry, respectively. Thermal shock tests were carried out to determine the bond strength of the coating with the steel substrate. The results indicate that the coating is composed of α-A1203, α-（Fe-Cr） and Al2SiO5 as the main phases. It is found that the coating with the diluents of Al2O3-SiO2 and transition layer of Al2O3-Cr presents the hi.ghest hardness of 2270 HV0.2 and the lowest porosity of 3.93 %. Owing to a metallurgical bond of the coating-to-substrate, the coating exhibits a good thermal shock resistance.展开更多
The phytophagous miteTetranychus truncatusis a serious pest in East Asiabut has a relatively narrower host range than the pest miteTetranychus urticae,which canfeed on over 1200 plant species.Here,we generated a high-...The phytophagous miteTetranychus truncatusis a serious pest in East Asiabut has a relatively narrower host range than the pest miteTetranychus urticae,which canfeed on over 1200 plant species.Here,we generated a high-quality chromosomal levelgenome ofT.truncatusand compared it with that ofT.urticae,with an emphasis on thegenes related to detoxification and chemoreception,to explore the genomic basis under-lying the evolution of host range.We also conducted population genetics analyses(in 86females from 10 populations)and host transfer experiments(in 4 populations)to investi-gate transcription changes following transfer to a low-quality host(Solanum melongena,eggplant),and we established possible connections between fitness on eggplant and genesrelated to detoxification and chemoreception.We found thatT.truncatushas fewer genesrelated to detoxification,transport,and chemoreception thanT.urticae,with a particularlystrong reduction in gustatory receptor(GR)genes.We also found widespread transcrip-tional variation amongT.truncatuspopulations,which varied in fitness on eggplant.Wecharacterized selection on detoxification-related genes throughωvalues and found a nega-tive correlation between expression levels andωvalues.Based on the transcription results,as well as the fitness and genetic differences among populations,we identified genes po-tentially involved in adaptation to eggplant inT.truncatus.Our work provides a genomicresource for this pest mite and new insights into mechanisms underlying the adaptation ofherbivorous mites to host plants.展开更多
基金financially supported by the Ministry of Education of China (No. 625010312)the Research and Innovation Project for College Graduates of Jiangsu Province, China (No. CXZZ13_0245)
文摘The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-coated layer on the binding structure and surface qual- ity of the coating were systematically investigated. The macrostructure, phase composition, and bonding interface between the coating and the substrate were investigated by scanning electronic microscopy （SEM）, X-ray diffraction （XRD）, and energy-dispersive X-ray spectrometry （EDS）. The diffraction patterns indicated that the coating essentially consisted of α-Al2O3, Fe（Cr）, and FeO-Al2O3. With an increase in the thickness of the pre-coated working layer, the coating became more smooth and compact. The transition layer played an important role in enhancing the binding between the coating and the substmte. When the pre-coated working layer was 10 mm and the pre-coated transition layer was 1 ram, a compact structure and metallurgical bonding with the substrate were obtained. Thermal shock test results indicated that the ceramic coating exhibited good thermal shock resistance when the sample was rapidly quenched from 800℃ to room temperature by plunging into water.
基金financially supported by the Ministry of Education of China(No.625010312)
文摘Al2O3-metal composite coatings with different reactants and diluents were fabricated on mild steel plate with nonpressure combustion synthesis process. The coat-ings were characterized by means of X-ray diffraction, scanning electron microscopy, and energy-dispersive spec-trometry, respectively. Thermal shock tests were carried out to determine the bond strength of the coating with the steel substrate. The results indicate that the coating is composed of α-A1203, α-（Fe-Cr） and Al2SiO5 as the main phases. It is found that the coating with the diluents of Al2O3-SiO2 and transition layer of Al2O3-Cr presents the hi.ghest hardness of 2270 HV0.2 and the lowest porosity of 3.93 %. Owing to a metallurgical bond of the coating-to-substrate, the coating exhibits a good thermal shock resistance.
基金supported by a grant-in-aid for Scientific Research(32020103011,U2003112,32202290,32161143014)from the National Natural Science Foun-dation of China.We thank Jia-Huan Guan and Qi-Qi Hufor their assistance in collecting biological materials.
文摘The phytophagous miteTetranychus truncatusis a serious pest in East Asiabut has a relatively narrower host range than the pest miteTetranychus urticae,which canfeed on over 1200 plant species.Here,we generated a high-quality chromosomal levelgenome ofT.truncatusand compared it with that ofT.urticae,with an emphasis on thegenes related to detoxification and chemoreception,to explore the genomic basis under-lying the evolution of host range.We also conducted population genetics analyses(in 86females from 10 populations)and host transfer experiments(in 4 populations)to investi-gate transcription changes following transfer to a low-quality host(Solanum melongena,eggplant),and we established possible connections between fitness on eggplant and genesrelated to detoxification and chemoreception.We found thatT.truncatushas fewer genesrelated to detoxification,transport,and chemoreception thanT.urticae,with a particularlystrong reduction in gustatory receptor(GR)genes.We also found widespread transcrip-tional variation amongT.truncatuspopulations,which varied in fitness on eggplant.Wecharacterized selection on detoxification-related genes throughωvalues and found a nega-tive correlation between expression levels andωvalues.Based on the transcription results,as well as the fitness and genetic differences among populations,we identified genes po-tentially involved in adaptation to eggplant inT.truncatus.Our work provides a genomicresource for this pest mite and new insights into mechanisms underlying the adaptation ofherbivorous mites to host plants.
