Surface Modification of Fine Diamond Grains by High-Frequency Magnetron Sputtering

在数控镜面磨削的情况下，自由成形模具的精加工工艺应采用具有细晶粒和上级耐磨性的球形金刚石砂轮。一种电镀金刚石工具，其中金刚石颗粒用镍离子电沉积，与通过粉末冶金工艺生产的常规轮相比，该电镀金刚石工具表现出上级耐磨性。然而，重要的是给予的形状精度和工具的磨削性能，因此只有一个单层的金刚石颗粒电镀在工具主体上。因此，工具主体上的单层金刚石颗粒的切削刃保持锋利的工具寿命是有限的。通过使用其中用镍离子电沉积厚堆叠的金刚石颗粒的电铸工具，可以增加电镀工具的工具寿命。然而，传统的沉积物共沉积技术需要非常长的时间来生产厚涂层，因为必须重复进行由剧烈搅拌、漂浮颗粒的沉积和电沉积组成的一系列过程。本研究针对传统技术的缺点，发展一种低速搅拌技术，以制造具有高晶粒密度的厚复合涂层。高速电铸是通过以低速搅拌沉积的颗粒以增加导电性来进行的。此外，通过用氧化物涂层覆盖颗粒表面，增加了金刚石颗粒对粘结材料的夹持强度。

A spherical diamond wheel with fine grains and superior wear resistance should be adopted for the finishing process of free-formed dies and molds in cases where numerically controlled mirror grinding is performed. An electroplated diamond tool in which diamond grains are electrodeposited with nickel ions exhibits superior wear resistance compared with conventional wheels produced by the power metallurgy process. However importance is given to shape accuracy and grinding performance of the tool, thus only a single layer of diamond grains is electrodeposited on the tool body. Hence, the tool life in which the cutting edges of the single-layered diamond grains on the tool body remain sharp is limited. The tool life of the electroplated tool can be increased by using an electroformed tool in which thickly stacked diamond grains are electrodeposited with nickel ions. However, the conventional sediment codeposition technique requires an extremely long time for the production of thick coatings, since a series of processes consisting of vigorous agitation, sedimentation of floating grains and electrodeposition must be conducted repeatedly. In this study, a low-speed agitation technique is newly developed to produce thick composite coatings with high grain density to overcome the disadvantages of conventional techniques. High-speed electroforming is conducted by agitating sedimented grain particles at a low speed to increase the electric conductivity. In addition, the gripping strength of diamond grains to the bond material is increased by covering grain surfaces with oxide coatings.