Key Engineering Materials Vols. 304-305

Abstract: In this paper, we report that the experimental results of fabricated diamond-metal composite film. Electrotyping method was used to deposit the thick film. During the deposition, low internal stress electrolytic solution, the electric current density of cathode, PH value, temperature, the distance between cathode and anode, the pretreatment of motherboard cathode were selected simultaneously. It was found that stirring strongly affected the quality of the film. Especially stirring velocity affected the distribution of diamond grains. Scanning electron microscope (SEM), X-ray photoemission spectroscopy (XPS) and X-ray diffraction (XRD) were used to measure the surface morphology, the crystal microstructure, diamond grains distribution and the chemical environment of the film.

Abstract: Being a key step in grinding process, dressing of grinding wheel influences the whole grinding results, especially grinding quality. Because of its good dressing effect, a new dressing method assisted by ultrasonic vibration attracted researchers’ attention. In this paper, on the basis of the researches on dressing with single-point diamond dresser, physical model of ultrasonic dressing of grinding wheel were established. According to the physical model and the SEM photos of grinding wheel’s surface topography, the mechanism of ultrasonic dressing was brought to light. Through contrast experiments, based on roughness and micro-feature of the ground surface, the influence of ultrasonic dressing on grinding quality was researched.

Abstract: In an abrasive tool the abrasive is the main part undertaking grinding work, thus, the grinding effects mainly depend on the types and properties of the abrasive. The strength and fracture property of the abrasive grain in a synthetic diamond abrasive tool have a direct influence on the operational performance of the tool. Generally, it is expected that the strength and protrusion height of the grain are as same as possible. The strength and fragmenting property of the abrasive grain hinge on its crystal shape and regularity and completeness, internal vice, impurity content and impurity distribution pattern. The abrasive grains must be sorted and classified to make their grain sizes and their properties consistent with each and all. In this paper, the author discusses the basic properties and related performances of synthetic diamond abrasives. Elementary discussion is made separately on improving the vibration sorting, introducing the magnetic separation, applying the heavy liquid separation, exploring the floatation technology and using the selective fragmentation principle. In addition, here are presented the basic methods for precise sorting of synthetic diamond abrasives and their general principles. Practices have proved these methods effective and feasible.

Abstract: This paper conducted Electro-Contact Discharge (ECD) dressing experiment for #600 diamond grinding wheel to understand how fine diamond grits protrude from metal-bonded wheel surface. The SEM observation, EDS analysis, image processing and 3D grit modeling on wheel surface were carried out to investigate grit protrusion characteristics. Then ECD dressing and mechanical dressing experiments were carried out to identify the effect of grit protrusion feature on grinding performance. It is confirmed that the dressed wheel surface topography is sensitive to open circuit voltage Ei, discharge polarity and electrode composition. Meanwhile, ECD dressing with Ei=15V and straight polarity can produce superior protrusion topography without the damage of diamond crystal faces and the bond tail behind protrusive grit. It can obtain better ground surface of hard-brittle material than mechanical dressing with the bond tail.

Abstract: Bonds of electroplated diamond tools are investigated through the studies of microstructures and properties. Three coatings for tool bonds, nickel, nickel-cobalt and bright nickel, were fabricated with electrodeposition processes, and were heat-treated with different temperatures. The hardness and microstructures of coatings were measured and observed. Optical glass K9 was machined with fabricated electroplated diamond tools to compare material removal rate and grinding ratio. The grain sizes of three bond coatings are different. The laminar structures of nickel-cobalt and bright nickel coatings turn to fine columnar structure after heat treatment processes. With heat treatment of 200°C temperature, bright nickel electroplated diamond tool presents highest values of material removal rate and grinding ratio. The research results show that better microstructures and property of bond for electroplated diamond tool can be obtained by selecting proper electroplating technology and heat treatment processes.

Abstract: As one of the excellent decorative materials ceramic tiles must be ground and polished to present the glossy surface. In this paper the ceramic tiles were edge ground by diamond cup wheels in the special designed test machine. The surface morphology of the polished ceramic tiles and the wear of diamond cup wheel were examined by Scanning electron microscopy (SEM). The wear resistance of diamond cup wheel and the materials’ removal process of ceramic tiles had been tested. The results showed that the wear of diamond cup wheel was stable when grinding with high grinding ratio. The ground surface showed that only the fracture of ceramic tiles was acted by diamond grits during grinding with water by means of good quality diamond cup wheel.

Abstract: This paper discussed the principle about the Electrical Discharge Truing(EDT) technique ,which applied in lapping machining process, including EDT status with different environment and machining conditions, and an EDT equipment on a lapping machine have been developed and used in the experiment of EDT. Then some experiments were carried out for verifying of the EDT effect with different EDT parameters such as electric voltage, EDT gap, and the EDT media. Finally, the efficient and precision EDT was achieved with the suitable EDT parameters.