The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite cons...The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.展开更多
Titanium cenosphere syntactic foam of varying relative densities with coarse cenospheres was developed through powder metallurgy route at lower compaction loads. The cold compaction load was varied in the range of 60 ...Titanium cenosphere syntactic foam of varying relative densities with coarse cenospheres was developed through powder metallurgy route at lower compaction loads. The cold compaction load was varied in the range of 60 to 75 MPa to obtain the foams of different relative densities. A function of cold compaction load between crushing tendency of cenosphere and relative density was investigated. The compressive deformation behavior of these foams was studied, and empirical relationships among plateau stress, elastic modulus, densification strains and energy absorption are formulated considering their practical significance. The performance indices of the developed foam in comparison with dense titanium were studied and it was found that the foam is superior alternative to titanium for engineering applications.展开更多
In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was performed.The ConWep program,developed by the US A...In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was performed.The ConWep program,developed by the US Army,was used to simulate blast loading using ABAQUS/Explicit■.Drucker-Prager(D-P)plasticity model,concrete damage plasticity(CDP),and Johnson-Cook(J-C)plasticity models were used to define the behavior of the soil,concrete,and reinforcement,respectively.FE analysis was carried out to compare the damages to the superstructure with variation in the cross-sectional shapes of the tunnel under internal blast loading.Three tunnel shapes(circular,rectangular,and horseshoe cross-sections)were considered in the FE analysis.An explosive of 100 kg TNT was located at the center of the cross-section of the tunnel.The response of the tunnel in terms of displacement and stress at critical locations was computed.The results showed that changes in the cross-section of the tunnel affect the stability of the tunnel,even when keeping all other factors constant.It was observed that the intensity of the stresses was the highest for a rectangular tunnel and lowest for a circular tunnel.Furthermore,it was also determined that the tunnel with a rectangular cross-section experienced the maximum displacement in the reinforced concrete(RC)lining compared with the horseshoe and circular tunnels.The displacement measured at critical structural members of the superstructure was found to be the highest for the tunnel with a rectangular cross-section and lowest for the tunnel with a circular cross-section.展开更多
基金Financial supports from various funding agencies Tata Steel, Jamshedpur, Department of Science and Technology, New Delhi, Council of Scientific and Industrial Research, New Delhi and Board of Research on Nuclear Science, Bombay for the present study are gratefully acknowledged
文摘The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.
文摘Titanium cenosphere syntactic foam of varying relative densities with coarse cenospheres was developed through powder metallurgy route at lower compaction loads. The cold compaction load was varied in the range of 60 to 75 MPa to obtain the foams of different relative densities. A function of cold compaction load between crushing tendency of cenosphere and relative density was investigated. The compressive deformation behavior of these foams was studied, and empirical relationships among plateau stress, elastic modulus, densification strains and energy absorption are formulated considering their practical significance. The performance indices of the developed foam in comparison with dense titanium were studied and it was found that the foam is superior alternative to titanium for engineering applications.
文摘In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was performed.The ConWep program,developed by the US Army,was used to simulate blast loading using ABAQUS/Explicit■.Drucker-Prager(D-P)plasticity model,concrete damage plasticity(CDP),and Johnson-Cook(J-C)plasticity models were used to define the behavior of the soil,concrete,and reinforcement,respectively.FE analysis was carried out to compare the damages to the superstructure with variation in the cross-sectional shapes of the tunnel under internal blast loading.Three tunnel shapes(circular,rectangular,and horseshoe cross-sections)were considered in the FE analysis.An explosive of 100 kg TNT was located at the center of the cross-section of the tunnel.The response of the tunnel in terms of displacement and stress at critical locations was computed.The results showed that changes in the cross-section of the tunnel affect the stability of the tunnel,even when keeping all other factors constant.It was observed that the intensity of the stresses was the highest for a rectangular tunnel and lowest for a circular tunnel.Furthermore,it was also determined that the tunnel with a rectangular cross-section experienced the maximum displacement in the reinforced concrete(RC)lining compared with the horseshoe and circular tunnels.The displacement measured at critical structural members of the superstructure was found to be the highest for the tunnel with a rectangular cross-section and lowest for the tunnel with a circular cross-section.
