The tribological behaviors of Cu-15Ni-8Sn/graphite composites with the graphite content of 38 vol.%against AISI321 stainless steel under dry-sliding,deionized water and sea water were investigated on a block-on-ring c...The tribological behaviors of Cu-15Ni-8Sn/graphite composites with the graphite content of 38 vol.%against AISI321 stainless steel under dry-sliding,deionized water and sea water were investigated on a block-on-ring configuration.The results indicated that the friction coefficient was the lowest under dry-sliding,and the highest in deionized water.The wear rate decreased to reach the minimum value of 1.39×10-15 m3/(N·m)in sea water and in deionized water,it increased to the maximum value of 5.56×10-15 m3/(N·m).The deionized water hindered the formation of tribo-oxide layer and lubricating film,which resulted in the largest friction coefficient and wear rate.In sea water,however,the corrosion products comprised of oxides,hydroxides and chlorides were found on the worn surface,and the compacted layer composed of corrosion products and graphite played an important role in keeping the excellent wear resistance.It was elucidated that the tribological behaviors of Cu-15Ni-8Sn/graphite composite were powerful influenced by the friction environments.展开更多
The properties of the warp knitted spacer fabrics for pressure reduction are experimentally investigated and compared to other materials.The influences of the different parameters, such as thickness, spacer yarn diame...The properties of the warp knitted spacer fabrics for pressure reduction are experimentally investigated and compared to other materials.The influences of the different parameters, such as thickness, spacer yarn diameter and connecting form are also analyzed and discussed. The results have shown that the spacer fabrics have very good properties for pressure reduction when they are used as soles, mattress or cushions.展开更多
The amount of muddy soil generated from various kinds of construction sites is always problematic. It is very difficult to treat muddy soil because of its low strength and high water content. But, the reuse of muddy s...The amount of muddy soil generated from various kinds of construction sites is always problematic. It is very difficult to treat muddy soil because of its low strength and high water content. But, the reuse of muddy soil is necessary to reduce the total amount of industrial wastes. Surplus concrete is also in a similar situation. Coarse and fine aggregates are removed from surplus concrete as an intermediate treatment, however, concrete sludge still remains. The authors propose a reuse method that involves the muddy soil being mixed with concrete sludge as an improvement material. The possibility of the utilization of concrete sludge was investigated through laboratory experiments. As a result, it was found that the unconfined compressive strength of the improved soil mixed with concrete sludge increased as the curing proceeded.展开更多
Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced ceme...Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) fiber.Two different strength grades of PDCC were examined with cubic specimen size of 100 mm in the tests.The specimens were loaded with a servo-hydraulic jack at different stress ratios.The principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were examined.The test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete material.For the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of fibers.Finally,a failure criterion was proposed for PDCCs under biaxial compression.展开更多
基金Project(51674304) supported by the National Natural Science Foundation of ChinaProject(19B430013) supported by the Key Scientific Research Projects of Higher Education Institutions in Henan Province,ChinaProject(2017BSJJ013) supported by the Doctor Research Foundation of Zhengzhou University of Light Industry,China
文摘The tribological behaviors of Cu-15Ni-8Sn/graphite composites with the graphite content of 38 vol.%against AISI321 stainless steel under dry-sliding,deionized water and sea water were investigated on a block-on-ring configuration.The results indicated that the friction coefficient was the lowest under dry-sliding,and the highest in deionized water.The wear rate decreased to reach the minimum value of 1.39×10-15 m3/(N·m)in sea water and in deionized water,it increased to the maximum value of 5.56×10-15 m3/(N·m).The deionized water hindered the formation of tribo-oxide layer and lubricating film,which resulted in the largest friction coefficient and wear rate.In sea water,however,the corrosion products comprised of oxides,hydroxides and chlorides were found on the worn surface,and the compacted layer composed of corrosion products and graphite played an important role in keeping the excellent wear resistance.It was elucidated that the tribological behaviors of Cu-15Ni-8Sn/graphite composite were powerful influenced by the friction environments.
文摘The properties of the warp knitted spacer fabrics for pressure reduction are experimentally investigated and compared to other materials.The influences of the different parameters, such as thickness, spacer yarn diameter and connecting form are also analyzed and discussed. The results have shown that the spacer fabrics have very good properties for pressure reduction when they are used as soles, mattress or cushions.
文摘The amount of muddy soil generated from various kinds of construction sites is always problematic. It is very difficult to treat muddy soil because of its low strength and high water content. But, the reuse of muddy soil is necessary to reduce the total amount of industrial wastes. Surplus concrete is also in a similar situation. Coarse and fine aggregates are removed from surplus concrete as an intermediate treatment, however, concrete sludge still remains. The authors propose a reuse method that involves the muddy soil being mixed with concrete sludge as an improvement material. The possibility of the utilization of concrete sludge was investigated through laboratory experiments. As a result, it was found that the unconfined compressive strength of the improved soil mixed with concrete sludge increased as the curing proceeded.
基金supported by the National Natural Science Foundation of China (Grant No. 51278118)the National Basic Research Program of China ("973" Program) (Grant No. 2009CB623200)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) fiber.Two different strength grades of PDCC were examined with cubic specimen size of 100 mm in the tests.The specimens were loaded with a servo-hydraulic jack at different stress ratios.The principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were examined.The test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete material.For the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of fibers.Finally,a failure criterion was proposed for PDCCs under biaxial compression.
