Pressureless Bonding of 3Y-TZP to Titanium

Abstract

The pressureless bonding of 3Y-TZP and Ti metal using a bonding agent containing Cu₂O-added 5 wt% activated carbon as a reductant has been investigated. The test specimen consisting of two kinds of the materials in question with the bonding agent interposed between the two has been heat-treated at 1000°C for 0min to 8h, exposed in an argon stream. The average strength of the test specimens bonded under the conditions of 4°C/min of heating rate and 30min of treatment time was 53MPa. An observation of the interfacial composition and an analysis of the micro-constituents have been performed with the bonded body thus obtained, employing EPMA and SEM with an energy-dispersive-type X-ray analyser. As the result, Cu produced by the carbon reduction of Cu₂O is diffused into the Ti metal to form CuTi₂. It has been made known that the structure of the bonded interface comprised of plural layers is as shown below. The reaction layers from 3Y-TZP sequential to Ti metal are titanium oxides layer (TiO, Ti₂O)/Ti-rich layer (Ti with scanty Cu)/Cu-Ti alloy layer (CuTi₂). The most effective parameters affecting the bonding strength are surface roughness of TZP and heating rate when heat-treatment is conducted. The bonding strength obtained by utilizing a specimen of TZP with 3μm of surface roughness and 20°C/min of heating rate for 30min of treatment time was higher than 110MPa. None of strength degradation has been noticed at all with the bonding strength of the bonded bodies thus obtained in Ar gas, N₂ gas, and the air up to 1000°, 800° and 400°C, respectively. The result implies that the bonded bodies are thermally stabilized.