Composition dependence of mechanical properties of diamond segments

This research is devoted to studying the mechanical characteristics of diamond-drilling-tool matrix. The infiltration method at a temperature of 1100–1150°C for 15 min in hydrogen medium was used for making model diamond-containing and diamond-free samples of 24 × 7 × 8 mm matrices of two types differing in content of nickel and fused tungsten carbide, namely WC-Co-Cu (1) and WC-Co-Cu-Ni + cast tungsten carbide (2). A8K160 (500/400 μm), AC50 (500/400 μm), and SDB1125 (30/40 mesh, i.e., 600/425 μm) diamonds were used as diamond-filling materials with a concentration of 9 vol % in the matrix. The bending strength, hardness, density, porosity, and abrasive resistance of drilling tool matrix samples are measured. It is found that WC-Co-Cu-Ni matrix samples have higher hardness and abrasive resistance when compared with WC-Co-Cu, which is explained by the occurrence of nickel and solid particles of tungsten carbide solids in them. The introduction of diamonds in the matrices results in a substantial increase in their hardness (by 8–10 HRC units), which distorts the hardness measured data of matrices in the diamond layer of drill crowns.     

Pressure dependence of collagen melting

Calf skin collagen type I and interstitial collagen of the annelids Alvinella pompejana and Riftia pachyptila were thermally unfolded at pressures of 1 and 200 bar. The high pressure was near the habitat pressure of the annelids which live in deep sea hydrothermal vents. The transition temperature increased with pressure by only 1.4 +/- 1 degrees C for calf skin collagen, and no pressure effect was detectable for the annelid collagens. The value for calf skin collagen agrees with prediction based on published values of the transition volume and transition enthalpy. The triple helices of the interstitial collagens of the annelids, which have melting temperatures of 46 degrees C (Alivinella pompejana) and 29 degrees C (Riftia pachyptila), are not further stabilized by pressure.