Advanced Materials Research Vols. 69-70

Abstract: For producing ultra smooth surface, a nanoparticle colloid jet machining system has been designed and manufactured in which a reversible polymerize and decompose reaction is utilized to remove surface atoms. The material removal characteristics of nanoparticle colloid jet machining were analyzed. A series of removal experiments were conducted to show the characteristics of the material removal in nanoparticle colloid jet machining. A K9 glass sample had been polished by using the nanoparticle colloid jet machining system, and an ultra smooth surface with micro roughness less than 1 nm RMS had been obtained. The experimental results prove that it is suitable to fabricate ultra smooth surface with nanoparticle colloid jet machining.

Abstract: The rough surfaces and non-uniform thicknesses of chemically vapor-deposited (CVD) diamond films and substrates affect their industrial application. In recent years, many polishing and planarization methods have been reported, but each method has its relative merits. This paper reviews the necessity for processing of the CVD diamond films first. Then the processing mechanism of micro-cracking and the characteristics of mechanical polishing of diamond films are discussed. The remove form of the material and surface characteristics are compared by three mechanical polishing method, including free abrasive polishing, fixation abrasive polishing and membrane on the membrane polishing method. No matter what form of mechanical polishing process is adopted, because of its inherent characteristics and the principles of processing, mechanical polishing CVD diamond films can only be as polish processing to remove large residual. The macro-surface roughness of processing is about the 2μm. The micro-rough surface roughness is for the 40nm or so. The material removal rate is 10nm/h.

Abstract: Mould manufacturing involves a large number of groove, slot, hole, prism, pyramid and narrow special-shaped surface called structural surface. Such particularity of these structural surface has caused restrict to the exposure between the grinding, polishing electrode tools and the covered processing surface. So General polishing machining can not be used for such precision surface processing. At present, In mould field, the requirement of the structural surface increasingly need high quality, For example, precision injection mould, not only the die face of the injection mould but the injection mould shoot also has high roughness demands. As the structural surface machining is difficult to use contact-machining tools (such as polishing or grinding), even if the manual operation is also very difficult (because manual operation also needs the auxiliary tools).So the precision processing of the mould structural surface has become an urgent unresolved problem. But now it still lack of intensive research. In order to solve the problem, we raise a new tool-free principle based on the liquid-solid two phase abrasive flow machining.

Abstract: In micro-cutting, the uncut chip thickness is comparable or even less than the tool edge radius and as a result a chip will not be generated if the uncut chip thickness is less than a critical value, viz., the minimum chip thickness. Knowledge of the minimum chip thickness plays a key role of the selection of appropriate machining conditions and optimization the micro-cutting processes. An analytical model is developed to predict the minimum chip based on the strain gradient plasticity theory in this paper, and the model accounts for the effect of material property in micro-scale such as the shear modulus, intrinsic length scale, fracture toughness and the Burgers vector. Predicted results are validated by experimental data obtained from the orthogonal micro-cutting experiments.

Abstract: There has been increased interest in the use of SiC due to its excellent physical and mechanical properties. The diamond grinding process of SiC has been largely investigated in recent years, but the interface between diamond grain and SiC in grinding has not been completely understood. In this paper, a single diamond scratching method was presented in order to insight into the interface realizing on a SRV friction and abrasion test machine using three types of diamond grains with different shapes. The results analysis for material removal and diamond grain wear mechanisms in the interacting between the diamond grain and SiC can be useful to improve the grinding process of SiC.

Abstract: In order to increase the material removal rate of silicon wafer, composite abrasives slurry was used in CMP. The mechanism of interaction between silica abrasives and polymer particles was analyzed. Small silica abrasives were seen to attach onto the surface of the polymer particles. Composite abrasives slurry was obtained by adding polymer particles into single abrasive slurry. Three key parameters, the concentration of colloidal silica, the concentration of polymer particle and the speed of polishing, which influence the material removal rate of silicon wafer were analyzed by Taguchi method and the optimal parameters were obtained. Experimental results indicated that the maximum material removed rate of 353nm/min was obtained when optimal craft parameters of 5% colloidal silica, 3% polymer particle, 50rpm plate and carrier rotation speed were selected.

Abstract: The purpose of this paper is to study electrochemical micro machining (ECM) technology on stainless steel. The micro machining of stainless steel is difficult by electrochemical machining, especially in machining deep micro holes, because of an oxide layer formed on the surface. To machining stainless steel, HF is usually used in electrolyte to destabilize the oxide layer. In this paper, ECM of stainless steel by applying short pulses in less toxic and corrosive electrolyte is research. The influence of electrochemical machining parameters such as voltage, current, electrolyte composition to machine stainless steel was investigated. The results showed that the oxide layer can be reduced by adding chloride and complex.

Abstract: Silver electrode layer of piezoelectric ceramic transducer requires good surface quality and high efficiency. Efficiency of traditional lapping and polishing is very low. Ultra-precision grinding technology is also unsuitable for the thickness of workpiece is extremely thin. Semi bonded abrasive lapping is a new ultra-precision processing method. The new ultra-precise method can achieve good surface quality in short time, and removal stock of workpiece is small. In order to research the optimal technology of semi bonded abrasive lapping about silver electrode layer, this paper research several major processing parameters by experiments. The results show that appropriate processing load can obtain better surface roughness of silver electrode layer，and surface roughness of silver electrode layer has little change with different processing speed. By using ultra-fine semi bonded abrasive plate, 94.08KPa processing load and 40 rpm polishing speed, after 30 minutes, surface roughness of silver electrode layer is 11nm, and removal stock is 11.5μm.

Abstract: The machining of materials on microscopic scales is considered to be great importance to a wide variety of fields. Electrochemical Micro-machining (EMM) appears to be promising to machine the micro-structures in future due to the material is dissolved at the unit of ion. This paper is focused on developing a micro electrochemical machining system in which the micro-structures such as micro-cylinder, multiple micro-electrodes, micro-holes and micro-slot were processed. The micro-electrodes were prepared in a precisely controlling the electrochemical etching process. Mathematical model controlling the diameters of electrodes was built up. Furthermore, the obtained micro-electrodes were selected as the cathode tool for micro holes drilling and micro-slot milling using pulse power in Micro-ECM.

Abstract: This paper introduces the TFT-LCD (Tablet Film Transistor Liquid Crystal Displayer) module process that is composed by two stages, JI (JISO) process and MA (Module Assy) process. In JI process, the main defect phenomena are bonding particle and bonding defect, which have a bad effect on the product yield. In MA process, the key factor of the output is the inequality workload to every worker and unbalance of the production line. With the solution of plasma cleaning and pressure diversification, the bonding defect ratio descent from 0.34% to 0.14%. By making workload balance, the efficiency of MA process has been increased.