Coatings of metal matrix composites(Cu?WC)were fabricated by solid-state sintering.WC reinforcing particles indifferent quantities from5%up to30%(volume fraction)were mixed with Cu particles.After mixing,the powders w...Coatings of metal matrix composites(Cu?WC)were fabricated by solid-state sintering.WC reinforcing particles indifferent quantities from5%up to30%(volume fraction)were mixed with Cu particles.After mixing,the powders were poured ontothe surface of copper substrates.Sintering was carried out at1000°C under a reducing atmosphere in a vertical dilatometer.Sinteringkinetics was affected by both rigid substrates and WC particles which retarded the radial and axial densification of powders.However,the coatings were strongly attached to the substrate,and WC particles were randomly distributed within the matrix.The addition ofthe reinforcing particles enhanced the microhardness and reduced the volume loss in wear tests to1/17compared to the unreinforcedsample.The predominant wear mechanism was identified as abrasion at a load of5N.20%WC(volume fraction)reinforcingparticles led to the maximum values of properties for the composite coating.展开更多
Application of laser shock processing （LSP） on 6061-T6 aluminum was made in order to evaluate its response to the erosive wear by silica sand. Impact angles of 15° , 30° , 60° and 90° were tes...Application of laser shock processing （LSP） on 6061-T6 aluminum was made in order to evaluate its response to the erosive wear by silica sand. Impact angles of 15° , 30° , 60° and 90° were tested, two particle speeds （37 and 58 m/s） and two LSP irradiation conditions were used. Erosion marks were characterized by 3D profilometry and SEM analysis was conducted to identify the erosion mechanisms for each tested angle. The results showed a maximum erosive wear at low impact angles （ductile type behavior）. Erosion strength and the erosion mechanisms were not affected by the application of LSP and they were attributed to the high strain rate of the erosion phenomena. A few differences encountered on the erosion plots were explained on the basis of the surface roughness left by the LSP process. The maximum mass loss and the maximum erosion penetration happened in different impact angles （15° and 30° , respectively）. Finally, a well-defined erosion mechanism transition was observed, from cutting action at low impact angle, to crater formation at 90° of incidence.展开更多
A ternary Ni_(2)FeSb shape memory alloy was fabricated by powder metallurgy route.Sintering kinetics was estimated from dilatometry tests;whereas the microstructure and morphology of the powder and consolidated bulk s...A ternary Ni_(2)FeSb shape memory alloy was fabricated by powder metallurgy route.Sintering kinetics was estimated from dilatometry tests;whereas the microstructure and morphology of the powder and consolidated bulk samples were evaluated by XRD and SEM,respectively.Microhardness tests were performed on the surface of sintered samples.The results indicated that milling time has an effect on the shape and particle size as well as the homogeneity of the crystalline structures of the powders.Samples with longer milling time presented higher relative densities,better distribution of the elements on the alloy as well as the L21 and martensite phases,which will give the shape memory effect.The estimated activation energy values ranged from 109 to 282 kJ/mol at temperatures between 750 and 1273 K,indicating that sintering is controlled mainly by volume diffusion.Microhardness was improved by increasing the milling time and the heating rate.展开更多
基金CONACy T through the project CB-167111the Scientific Research Department of the UMSNH and the Guadalajara University for the financial support and the facilities to develop this study
文摘Coatings of metal matrix composites(Cu?WC)were fabricated by solid-state sintering.WC reinforcing particles indifferent quantities from5%up to30%(volume fraction)were mixed with Cu particles.After mixing,the powders were poured ontothe surface of copper substrates.Sintering was carried out at1000°C under a reducing atmosphere in a vertical dilatometer.Sinteringkinetics was affected by both rigid substrates and WC particles which retarded the radial and axial densification of powders.However,the coatings were strongly attached to the substrate,and WC particles were randomly distributed within the matrix.The addition ofthe reinforcing particles enhanced the microhardness and reduced the volume loss in wear tests to1/17compared to the unreinforcedsample.The predominant wear mechanism was identified as abrasion at a load of5N.20%WC(volume fraction)reinforcingparticles led to the maximum values of properties for the composite coating.
文摘Application of laser shock processing （LSP） on 6061-T6 aluminum was made in order to evaluate its response to the erosive wear by silica sand. Impact angles of 15° , 30° , 60° and 90° were tested, two particle speeds （37 and 58 m/s） and two LSP irradiation conditions were used. Erosion marks were characterized by 3D profilometry and SEM analysis was conducted to identify the erosion mechanisms for each tested angle. The results showed a maximum erosive wear at low impact angles （ductile type behavior）. Erosion strength and the erosion mechanisms were not affected by the application of LSP and they were attributed to the high strain rate of the erosion phenomena. A few differences encountered on the erosion plots were explained on the basis of the surface roughness left by the LSP process. The maximum mass loss and the maximum erosion penetration happened in different impact angles （15° and 30° , respectively）. Finally, a well-defined erosion mechanism transition was observed, from cutting action at low impact angle, to crater formation at 90° of incidence.
基金PROMEP/103.5/13/6992 and the CIC of the UMSNH for the financial supportCONACYT under the project CB-2011-167111
文摘A ternary Ni_(2)FeSb shape memory alloy was fabricated by powder metallurgy route.Sintering kinetics was estimated from dilatometry tests;whereas the microstructure and morphology of the powder and consolidated bulk samples were evaluated by XRD and SEM,respectively.Microhardness tests were performed on the surface of sintered samples.The results indicated that milling time has an effect on the shape and particle size as well as the homogeneity of the crystalline structures of the powders.Samples with longer milling time presented higher relative densities,better distribution of the elements on the alloy as well as the L21 and martensite phases,which will give the shape memory effect.The estimated activation energy values ranged from 109 to 282 kJ/mol at temperatures between 750 and 1273 K,indicating that sintering is controlled mainly by volume diffusion.Microhardness was improved by increasing the milling time and the heating rate.
