X.L.Gong
,
Y.Liu
,
S.Y.He
,
J.Lu
材料科学技术（英文）
Three types of metal porous polymer composite (MPPC) were produced by infiltrating different polymers into a porous Al structure. This type of interpenetrating microstructure allows for a better combination of mechanical and physical properties. The low velocity impact response of these composites was investigated by conducting drop-weight impact tests. Impact parameters such as the peak load, the time to peak load, the deflection at peak load, and the absorbed energy were evaluated and compared for Al, MPPC and pure Al foam. The influence of the volume fraction of polymer was also investigated for the above impact parameters. The experimental results indicate that the inlaid polymer has a very important positive effect on the impact behavior and improves the characteristics of the composite in comparison with conventional foam and pure Al.
关键词:
MPPC
,
null
,
null
T.Rol
,
M.Ya
,
D.Retraint
,
K.Lu
,
J.Lu
材料科学技术（英文）
Surface mechanical attrition treatment (SMAT) can produce a nanometer-grained surface layer without porosity and contamination on a bulk stainless steel. The nanostructured layer has high strength that contributes to an overall increase in the mechanical properties of the nanostructured sample. In this study, a new nanostructured composite was developed by assembling three SMA-treated thin plates. An FEM model based on nanoindentation data was established to simulate the stress-strain relationship. The simulation and the experimental tension curve correspond well. Moiré interferometry was used to observe the tensile behavior of the new composite in real time. A tension test conducted on a specimen consisting of three 500~μm thick SMA-treated sheets showed that the yield stress is much higher than that of a bulk-treated sample of the same total thickness. Based on these results, the new multilayer composite would seem to be a promising structural material due to its high strength/weight ratio.
关键词:
Nanostructures
,
null
,
null
,
null
G.Montay
,
A.Cherouat
,
A.Nussair
,
J.Lu
材料科学技术（英文）
Residual stress in coatings is the result of individual particle stress. Their effects may be either beneficial or detrimental, depending upon the magnitude, sign and distribution of the stresses with respect to the external load. Tensile stress which exceeds the elastic limit causes cracking in surface coatings or at the interface between the substrate and the coat. Compressive stress, in general, has a beneficial effect on the fatigue life, crack propagation, coating adhesion and on the durability of the top coat during service. Compressive residual stresses can increase the number of cycles before crack initiation begins through a mean stress effect. Temperature gradients which occur during solidification and subsequent cooling are the principal mode of internal stresses generation. Some parameters influence the residual stress field of both the coating and the substrate. Substrate nature, spraying temperature, thickness of the coat layer, substrate preparation (grit blasting conditions), and velocity of the splats are in the relation with the quality of the coating. In this work, we will describe the role playing by the ceramics coating elaboration on the residual stress gradient in depth of the component. The incremental hole drilling technique has been developed to determine the residual stress gradient in depth of the coat and substrate which must be used with particularly conditions. This new technology has been employed on zirconia, alumina and tungsten carbide plasma sprayed coating.
关键词:
Coating
,
null
,
null
,
null
