Papers by Keyword: Nickel Layer

Abstract: A production-scale multiwire saw machine and 4 inch sapphire ingots were used in this study. The diamond wire used in the study had a core diameter of 0.1mm with an attached diamond particle size of 8–12μm. This study uses the Taguchi method and Grey relational analysis on the key diamond wire parameters which are electroplated nickel layer thickness, diamond wire tension, diamond wire speed and sapphire ingot feed rate, in order to simultaneously optimize the cutting performance in the diamond wire sawing of sapphire ingots. Based on the analysis, the nickel layer thickness and wire speed are the first and second most significant factors with 31.7 and 29.9% effects on cutting performances. The optimal control factors were then simultaneously evaluated for Ra, material removal rate, diamond wire wear rate and TTV and were found at optimization to be 14 μm nickel layer thickness, 15NT wire tension, 800m/min wire speed and 0.2mm/min feed rate, respectively. Compared with current standard condition, this improved process obtained from the optimization of diamond wire electroplated nickel layer thickness and saw machine parameters in the diamond wire sawing of sapphire ingots can achieve a 33% lower Ra, a 20% lower diamond wear rate, a 13% lower TTV and a 20% higher material removal rate, simultaneously.

Abstract: Nickel enables nucleation and growth of well oriented diamond crystals from the small lattice mismatch between nickel and diamond. However, its solubility for carbon causes carbon loss during diamond deposition and, consequently, results in poor nucleation density. In this study, carburizing of Ni/WC-Co specimens in high temperature furnace with inert gas atmosphere was adopted to provide nickel with sufficient carbon prior to diamond deposition. This process was carried out using charcoal powder as source of carbon at different treatment temperatures (750°C and 850°C) and durations (20min and 60min). Effect of the process in altering the nickel layer composition was characterized by microscopy, element analysis, and phase identification techniques. Results show that carburization leads to formation of metallic phases, such as nickel carbide and nickel cobalt, which are considered beneficial for diamond nucleation and growth.