Precision grinding of a microstructured surface on hard and brittle materials by a microstructured coarse-grained diamond grinding wheel

Microstructured surfaces on hard and brittle materials are widely used in a series of scientific and industrial applications, such as micro-electro-mechanical systems, nano-electro-mechanical systems, electronic devices, and medical products. However, the efficient precision machining of microstructured surfaces on hard and brittle materials faces great challenges. In this study, a new machining technology for high-efficiency precision fabrication of microstructured surface on hard and brittle materials was developed by a microstructured coarse-grained diamond grinding wheel. Initially, the laser microstructuring of the conditioned coarse-grained diamond grinding wheel was introduced. The influence of the laser-machined microstructure geometry on the form accuracy of the final, ground microstructured surface was theoretically analysed. Subsequently, the ductile regime grinding of the microstructured surface was examined for WC cermet and BK7 optical glass. The ground surfaces mainly under the ductile regime material removal were successfully achieved, especially in the case of WC ceramic. Finally, different linear and square microstructured surfaces with high form accuracy, sharp microstructure edge, and nanoscale surface roughness were efficiently fabricated on WC and BK7 optical glass by the method developed in the study.     

钎焊金刚石／cBN砂轮基体工艺方法初探

针对目前国内制作钎焊金刚石／cBN砂轮的几种工艺方法,分析了其中存在的优缺点。根据工厂试验中出现的实际问题：焊接的温度对砂轮基体硬度影响较大,进而影响了对精度的保持,文章指出了寻找合适基体材料的方法。为解决高温钎焊对基体的影响提供了一个较好的样本。要满足cBN／金刚石砂轮基体的力学性能需要,建议砂轮基体采用40Mn2这种材料,在700℃左右回火,其硬度可以达到HRC38左右,能够满足高速磨削和高精度磨削的要求。     

Morphological evolution and grinding performance of vitrified bonded microcrystal alumina abrasive wheel dressed with a single-grit diamond

Dressing experiments under different conditions were carried out on a vitrified bonded microcrystal alumina abrasive wheel with a single-grit diamond dresser. The grinding performance of the as-dressed abrasive wheels was investigated. The dressing force, grinding force and the surface morphology of abrasive wheel and machined workpiece were studied to shed light on the relationship among the dressing processing vectors, morphology of abrasive wheel and the grinding performance. The results obtained show that the dressing forces increase with the increasing volume of the abrasive wheel material removed per unit time. The sensitive analysis reveals that the dressing feed speed take a greater effect than the single dressing depth on the dressing force. The self-sharpness of vitrified bonded microcrystal alumina abrasive wheel brings into some functions under certain dressing conditions, but a deep dressing depth would lead to an excessive abrasive self-sharpness, i.e. abrasive grits fall off and embed into the workpiece surface.     

Effect of BEO in the electrodeposition process of Ni/diamond composite coatings for preparation of ultra-thin dicing blades: Experiments and theoretical calculations

Ni/diamond dicing blades is the main tool for scribe of silicon wafer at present. In order to decrease the width of dicing slot on the wafer, it is necessary to reduce the thickness of blades, and to increase the hardness, toughness and wear resistance of the Ni/diamond composite coatings in the process of electrodeposition. In this paper, 1,4-bis(2-hydroxyethoxy)-2-butyne (BEO) was used as an organic additive in the composite baths containing nickel amino-sulfonate, nickel chloride, boric acid, sodium dodecyl sulfate (SDS) and diamond particles in sizes of 3–5?µm, in order to improve the properties of Ni/diamond coatings and produce ultra-thin Ni/diamond dicing blades. The textures of Ni/diamond composite coatings were mainly Ni (200) and Diamond (111) since the addition of BEO in the baths inhibited the growth of Ni (111) and Ni (220). Quantum chemical calculations and molecular dynamics (MD) simulations showed that BEO could adsorb at the nickel surface strongly and inhibit the electrodeposition of nickel atoms. With the increase in concentration of BEO in the baths, the cathodic polarization potentials shifted to more negative direction and the thicknesses of the coatings decreased. Adding the appropriate amount of BEO (0.1–0.2?g/L) in the baths, the roughness of the coating decreased the number of individual diamond particles in the coating increased, and the hardness and the wear resistance of the coating was improved. When the thickness of Ni/diamond composite coating on aluminum alloy wheeled substrate was 15?µm, the width of its dicing slot was 22?µm. However, the addition of BEO in the bath cannot change the adhesive wear mechanism of the coating.     

溶胶凝胶涂覆制备金刚石/陶瓷复合材料及其物理性能特点

制备陶瓷前体溶胶,溶胶混合金刚石微粉中形成凝胶,通过烧结得到金刚石/陶瓷块状复合材料。利用SEM、DSC、FTIR和XRD对样品进行表征,表明溶胶凝胶法可以使复合材料中碱金属的添加量得到控制。利用共振电路测量了片状复合材料在高频范围内的电阻和介电性能,发现当锂离子的摩尔含量在0.04时,10MHz下金刚石块状复合材料的介电损耗小于0.002。