Interfacial Shear Strength Measurements of SiC Fiber-Reinforced Titanium Composites

A continuous loading push-out test technique was used to measure the interfacial shear strength of SiC fiber reinforced Ti matrix composites. The interfacial shear strength of samples as-fabricated and after heat exposed at 700 and 800℃ for 50 h was successfully determined. It has been found that the interfacial shear strength of the specimen exposed at 700℃ was higher than that of as-prepared and exposed samples at 800℃. The shear strength of the as-prepared samples was about 112.45 MPa, and increased to about 153.77 MPa after heat-treating at 700℃ for 50 h, but decreased to 133.11 MPa after treating at 800℃ for 50 h. Scanning electron microscope （SEM） was used to investigate the interfacial morphology of the samples. The brittle phase was the main products of interface for samples exposed at 800℃, and the interface was easily peeled off.

Effect of Relative Reduction on Property of Steel-Mushy Cu-Graphite Composite

The rolling treatment of steel-mushy QTi3.5-3.5 graphite composite was conducted under different relative reduction at room temperature. The effect of room-temperature rolling on interracial mechanical property of steel-mushy QTi3.5-3.5 graphite composite was studied and the relationship between interracial shear strength and relative reduction was established. The results show that, for steel-mushy QTi3.5-3.5 graphite composite, which consists of 1.2 mm-thick 08AI steel plate and 2.8 mm-thick QTi3.5-3.5 graphite layer, there is a nonlinear relationship between interracial shear strength and relative reduction in graphite layer. When relative reduction is smaller than 1.1%,interracial shear strength increases with increasing the relative reduction. When relative reduction is larger than 1.1%, interracial shear strength decreases with increasing the relative reduction. When relative reduction is 1.1%,the largest interracial shear strength of 145.2 MPa can be obtained.

Influence of Pressing Time on Steel-copper-graphite Bonding

The bonding of steel plate with QTi3.5-3.5 graphite slurry was studied by using pressing bonding technique. The influence of pressing time on the interracial mechanical property of bonding plate was researched. The results show that： under the conditions of 620℃ preheating temperature of steel plate, 530℃ preheating temperature of dies, 46% solid fraction of QTi3.5-3.5 graphite slurry and 50 MPa pressure, there exists a nonlinear relationship between pressing time and interracial shear strength. The interracial shear strength of bonding plate increases with increasing pressing time and reaches a largest value about 127 MPa when pressing time is longer than 120 s. At the interface with the best mechanical property, there exists a continuous Fe-Cu inter-diffusion zone and a metallurgical bonding.

EFFECTS OF DIFFERENT FUNCTIONALIZATION SCHEMES ON THE INTERFACIAL STRENGTH OF CARBON NANOTUBE POLYETHYLENE COMPOSITE

The mechanical performance of carbon nanotube （CNT） reinforced polymer com- posites is primarily controlled by the dispersive capacity and interracial shear strength of CNTs in polymer matrices. CNT functionalizations will improve dispersion and strengthen interracial bonding of CNTs in matrices. To understand the effects of different functionalization schemes on the interracial strength of CNT-polymer composites, pullout of the covalent, noncovalent, and mixed functionalized single-walled carbon nanotube （SWCNT） from polyethylene （PE） matrix was simulated by using molecular dynamics, respectively. The results show that the SWCNT-PE interracial shear strength is significantly improved by SWCNT functionalizations, particularly by mixed functionalization.