Advanced Materials Research Vols. 76-78

Abstract: This paper introduces a new study on the modeling of AWJ necessary cutting energy. In the study, a model for prediction of the necessary cutting energy is proposed by combining physical-mathematical models and experimental methods. The effects of various jet parameters as well as the effects of the abrasive size, abrasive material and the effect of work material on the necessary cutting energy are taken into account.

Abstract: The abrasive waterjet machining is a powerful tool in processing various materials, especially, for brittle materials, such as ceramic, glass and so on. However, the material removal of a brittle material when impacted by abrasive waterjet is not understood in detail. In this paper, the material removal model in fracture erosion of brittle materials by abrasive waterjet has been developed.

Abstract: The application of abrasive technology in dentistry dates from 7000–9000 years. How does this ancient technology affect our modern society where the elderly population needs extensive dental care and ageing well and ageing productively is our first priority Many patients prefer tooth-colored, all ceramics restorations fabricated by dental CAD/CAM systems for reasons of esthetics, biocompatibility and high efficiency. In spite of the advantages of all-ceramic restorations, ceramic prostheses have not always performed as predicted or desired. Catastrophic fracture has been the most frequently reported reason for failure of all-ceramic restorations. This paper gives a brief review on abrasive technology in ceramic restorative dentistry to highlight problems to be solved by our abrasive technology community.

Abstract: The process of micro-powder blasting is the high speed gas flow which mixed the micro-particle and gas to impact the brittle substrate by the specialized nozzle. This paper combined various diameters Al2O3 eroding particle with a novel masking technique to fabricate the pattern channels in soda glass with a width to 2000 μm and depth down to 1631 μm. The masking technology for fabricating microchannel is consisted by the combination of two polymers: 1) the elastic and thermal-curable poly-(dimethyl siloxane) (PDMS) for its erosion resistance and 2) the brittle epoxy resin SU-8 for its photosensitivity. This paper discusses the processing procedure by the different processing parameters (micro-powder impact pressure, the distance between nozzle and substrate, micro-powder size, and micro-powder impact time) to find the optimal process. The results show that the micro-powder size is the most important factor for the depth of microchannel of microfluidic chip. The surface roughness of microchannel of microfluidic chip is nearly 5-6μm.

Abstract: The production of a compact chemical reactor called a micro channel device requires a glass microfabrication technique since it involves the formation of a micro channel on the surface of a glass substrate. We propose a direct mask drawing and micro blasting technique, designed to form a micro channel on a glass substrate. This method is suitable for producing a wide variety of patterns in small quantities. In conventional micro blasting the channel formed has a narrow base i.e. “V” shape cross-sections. Using a seesaw table to tilt the glass substrate during blasting, we can produce a wider based channel i.e. “U” shape cross-sections.

Abstract: It is important to obtain the optimal condition in wafer polishing processing. Polishing is one of the most important methods in manufacturing of Si wafers and in thinning of completed device wafer. This study will report the evaluation on abrasion of wafer according to processing time; machining speed and pressure which have the major influence on the abrasion of Si wafer polishing, for this, this study design the head unit and analysis head unit. After that, this study applies to experiment. The evaluation of abrasion according to processing condition is selected to use result data that measure a pressure, machining speed, and the processing time. This result is appeared by machining condition. Through that, the study can evaluate the abrasion characteristic of wafer in machining.

Abstract: This paper explores the effect of the depth-of-cut of an indenter on the phase transformations during nanoscratching on monocrystalline silicon on the Si(100) orientation. The analysis was carried out by molecular dynamics simulations. It was found that the depth-of-cut and the impingement direction of the indenter had a significant influence on the phase transformations in the initial impression region. At a relatively low depth-of-cut, only amorphous silicon was formed on the scratched surface. When the indenter impinged on a silicon surface with an angle, a bct5-Si crystalline phase in the initial impression region would emerge.

Abstract: A deconvolution method that combines nanoindentation and finite element analysis was developed to determine elastic modulus of thin coating layer in a coating-substrate bilayer system. In this method, the nanoindentation experiments were conducted to obtain the modulus of both the bilayer system and the substrate. The finite element analysis was then applied to deconvolve the elastic modulus of the coating. The results demonstrated that the elastic modulus obtained using the developed method was in good agreement with that reported in literature.

Abstract: It is known that silicon, during nanoindentation unloading, undergoes various phase transformations beneath the indenter. Investigations into the details are however not available. This paper studies the unloading behavior of silicon subjected to cyclic nanoindentations. The results show that the elastic unloading behavior of the material can be described by a power relationship, P = α∙hm, where P is the load, h is the elastic displacement, and α and m are material constants. It was found that the values of α and m were almost independent of the phase transition events, indicating that the elastic response of the material is mostly governed by the mechanical properties of Si-I phase while the influence of the phase transformations is negligible.

Abstract: Nanoindentation tests with the aid of acoustic emission monitoring were performed on single crystal MgO (001) plane to investigate the deformation of MgO under high indentation pressures. The results indicated that the deformation of MgO under nanoindentation with a sharp indenter could be classified into three stages: elastic deformation, elastoplastic deformation, and fragmentation. The elastic energy release and fracture occurred could be identified using acoustic emission signals.