Papers by Keyword: Advanced Ceramic

Abstract: Based on the analysis of problems of diamond cut-off wheels used in slot grinding of ceramics at present, a brazed diamond cut-off wheel was produced and analyzed. Two typical advanced ceramics, alumina and silicon nitride, were used as the workpiece materials. In the experiments of slot grinding of ceramics, grinding ratio, wear process of the wheel and grinding quality of the work were studied. Experimental results showed that the brazed diamond cut-off wheel obtained good grinding ratio and abrasive resistance. The surface roughness of ground silicon nitride was better than that of alumina.

Abstract: The rapidly growing market demand for nanoparticles calls for cost-effective and environmentally friendly technologies for their large-scale production. We developed a new, simple, economical and energy efficient synthesis of nanostructured complex oxides from inexpensive reactant mixtures, referred to as Carbon Combustion Synthesis of Oxides (CCSO). In CCSO the exothermic oxidation of carbon nanoparticles generates a steep thermal reaction wave that propagates through the solid reactant mixture converting it to the desired complex oxide product. CCSO is a modified form of SHS that maintains the advantages of SHS and circumvents some of its disadvantages. Specifically, it enables a more economical synthesis of complex oxides. The carbon used in CCSO is not incorporated in the product and is emitted from the sample as a CO2. A large gas emission provides a convective cooling mechanism trough the sample that significant reduces local temperature and prevents product partial melting and particles growth. CCSO does not require use of expensive fuel reactants and complex equipment and can be scaled up for continuous mass production. This paper reviewed the recent progress in the synthesis of advanced complex oxides nanoparticles by using carbon combustion process.

Abstract: This paper describes ultrasonically assisted fly cutting for finishing advanced ceramics for hot-press dies used to fabricate glass lenses. Fly cutting can perform shallow machining, which realizes ductile-mode cutting of hard, brittle materials. Ultrasonically assisted machining can increase the critical cutting depth (i.e., the maximum cutting depth for ductile-mode machining of a surface). The technique proposed in this paper combines both techniques and enables precise finishing of advanced ceramics at a high machining efficiency. Ultrasonic assisted fly cutting was found to reduce tool fracture and improve the finished surface quality compared with conventional fly cutting.

Abstract: As one of the cost-effective machining methods for advanced ceramics, rotary ultrasonic machining (RUM) has attracted much attention and there exist numerous publications on the process. However, few investigations on tool wear in the RUM process have been reported. This paper, for the first time in literature, presents an experimental observation on tool wear in RUM of alumina. it presents and discusses the results on tool wear in RUM of alumina. It also discusses some practical implications of the findings from this study.

Abstract: Ceramics are increasingly used in many advanced science and technology due to their excellent properties. Grinding is the most efficient and effective technique to achieve high dimensional accuracy and surface integrity of ground ceramic workpiece at optimum cost efficiency. The indentation/ scratch approaches are widely used in studying the grinding process. In this paper, the grinding technology and grinding induced damage of advanced ceramics are briefly reviewed. Based on MSC.Marc software, a FEM model for the Vicker’s indentation/scratch is established to simulate the abrasive grinding process, the stress and strain distribution in the advanced ceramics under a Vicker’s indenter are presented and discussed. The related elastic modulus is obtained by the nanoindentation tests.

Abstract: Using a variety of advanced ceramic materials, a comparison has been conducted of fracture toughness test methods using the single edge vee-notch beam method and the surface crack in flexure method, the latter restricted to optical fractography. Good agreement has been found between the two methods on materials which were amenable to the SCF method. It has further been shown that the SEVNB method can produce reliable results on materials to which the SCF method is not readily applicable.

Abstract: Rotary ultrasonic machining (RUM) is considered as an effective machining method, which has been utilized to machine hard and brittle materials such as advanced ceramics. In order to improve the hole wall surface quality during RUM, it is important to wash away swarf in the gap between the tool and the workpiece as fast as possible. In this paper, a new machine process – intermittent rotary ultrasonic machining (IRUM) – is introduced for the first time. The cutting force, surface roughness and coolant flow rate in conventional rotary ultrasonic machining (CRUM) process and IRUM process are compared. It is found that compared with CRUM, the output coolant flow rate could be increased significantly by using the IRUM method. It is also found that the surface roughness of workpiece can be improved significantly in IRUM.

Abstract: A new kind of polymer/layered silicate (PLS) nanocomposites-containing slurry was used to join green bodies of ZrO2 (8YSZ) and 95Al2O3 ceramics, without applied pressure. After sintering, a fine joint could be obtained without obvious cracks, pores and other defects, and the average flexural strength of the joints was comparable to that of the 95Al2O3 matrix. Effects of PLS on joining process were analyzed and the results showed suitability of PLS-containing slurry for green state joining ZrO2 to Al2O3 ceramics.

Abstract: The surface quality is a critical factor affecting the performance and reliability of advanced ceramics. This paper focuses on the application of Taguchi method for optimization of advanced ceramics lapping process parameters to obtain the best finish. An optimization experiment for lapping silicon wafer with Al2O3 was designed by Taguchi method. Surface roughness Ra and Rt are considered as criteria for optimization. Influence of parameters involving load, speed, and slurry concentration for a given workmaterial with given abrasive (material and size) are discussed, and the optimum lapping conditions are figured out. Compared with single parameter experimental results, it illustrates that the experiment design based on Taguchi method can successfully applied to determine the optimum processing conditions for advanced ceramics lapping process.

Abstract: Rotary ultrasonic machining (RUM) is one of the cost-effective machining methods for advanced ceramics, which is a hybrid machining process that combines the material removal mechanisms of diamond grinding and ultrasonic machining (USM). This paper presents an overview of the investigations on RUM of advanced ceramics. The issues about the material removal mechanisms, process modeling, material removal rate, and tool wear in RUM are reviewed. Directions of future research on RUM are also presented.