Materials Science Forum Vols. 471-472

Abstract: STEP-NC is a new CNC data interface proposed to replace ISO 6983, and has been partly formed into the draft international standard (ISO 14649). In this paper, the STEP-NC-based part program is analyzed, and the general methodology and tools for STEP-compliant application development are introduced. Then a framework for STEP-NC interpreter is proposed based on the SDAI method and the implementation solutions are presented. The EXPRESS compiler is used to convert the milling schema into C++ classes, and the information is extracted from the file in aid of data access tools. The said interpreter, which is fundamental to STEP-NC based machining, is also implemented with supporting tools in the ST-Developer environments. It is used to read the STEP-NC file into ROSE working form, and then extract and organize the manufacturing information in an object-oriented way.

Abstract: Ti(C0.7N0.3)-ZrO2-Ni-Mo cermet with 73.9%Ti(C0.7N0.3)-10%ZrO2-13%Ni-3.3%Mo(in mass) was fabricated by HP technology. The fabricated material possesses good mechanical properties with flexure strength (1264.4Mpa), fracture toughness (15 MPa.m1/2) and Vickers hardness (16.2GPa). The results of microstructure observation and analyses of the composite cermet by TEM, SEM and EDAX show that Mo2C nanoparticles are separated in the Ti(C,N) grains and the structure is similar to the “intragranular structure” in nanocomposite material. Smaller size t-ZrO2 and m-ZrO2 grains are distributed o n the boundaries of Ti(C,N) grains and the amount of m-ZrO2 is more than that of t-ZrO2.The growth of m-ZrO2 grain has an orientation on Ti(C,N) grain, which is propitious to the boundary bonding strength.

Abstract: Scanning probe microscopy (SPM) has proved to be a powerful tool not only for imaging but also for nanofabrication. SPM-based nanofabrication comprises manipulation of atoms or molecules and SPM-based nanolithography. SPM-based nanolithography, referred to as scanning probe lithography (SPL) in this review, holds good promise for fabrication of nanometer-scale patterns as an emerging generic lithography technique that STM, AFM, and SNOM are directly or otherwise used to pattern nanometer-scale features under appropriate conditions. Patterning methods including mechanical SPL, electrical SPL, thermal SPL, and optical SPL, are described in terms of SPL mechanisms. The newly developed variations of the above-mentioned SPL methods such as dip pen nanolithography, nanoshaving and nanografting, replacement lithography, constructive nanolithography, nanojet lithography, and electrostatic lithography, are also illustrated respectively. Analyses of prospective application of these SPL methods are presented finally.

Abstract: The paper describes a method to forecast the cohesive zone of blast furnace whose shape is very important for the quality of iron and the efficiency of iron-making industry. This method builds a model that can be observed during the operation of iron making. The model considers that during the chemical reaction the ore, the coke and the gas abide by two equations: the equation of conservation of mass and the equation of heat conservation. Based on this presumption, by dividing the blast furnace into a series of homocentric circles in the height direction and resolving the equations in every homocentric circle with its own parameters, we can get the relationship between temperature and height of the inner blast furnace. And then, according to the fusibility character of the ore, we can forecast the shape and position of the cohesive zone. Finally, the paper visualizes the cohesive zone of blast furnace and discusses some results achieved through the application of such method to a real blast furnace.

Abstract: In this paper, the formula of material removal rate (MRR) in wafer rotation grinding process is deduced based on kinematics. The main effect on MRR of the grit size and the process parameters, including the rotational speed of the cup grinding wheel, the down feed rate of the grinding wheel spindle and the rotational speed of the chuck table, is both theoretically and experimentally investigated. The influence on MRR of the cup wheel grinding status, the geometric dimension of the cup-grinding wheel, the rigidity of the grinding machine and the coolant is also analyzed. The investigating results show that, the increase of the grit size and the down feed rate of the cup grinding wheel results in great increase of the MRR; the MRR increases as the rotational speed of the cup wheel increases whereas the MRR reduces and the ground surface becomes bad due to size effect if the rotational speed of the cup wheel is overlarge; in normal grinding, the MRR decreases as the rotational speed of the chuck table increases. The results provide a theoretical basis to improve grinding efficiency, reduce grinding cost and select the proper parameters of grinding process.

Abstract: Ti(C, N) based ceramic tool materials in the Ti (C0.7N0.3)-(Ni-Co)-Cr3C2-VC system have been made by hot-pressing technology, their mechanical properties and fracture morphologies have been studied under three different fabrication conditions. The results show that the mechanical properties are significantly influenced by fabrication conditions, and the main fracture mode is intergranular fracture.

Abstract: In this paper, Based on regression analysis of tests, three comprehensive experimental models were presented in precision turning high-strength spring steel, Vicker’s hardness, residual stresses and surface roughness can be predicted utilizing these models. And the influence of tool geometry on machined surface integrity was analyzed systematically. The analytical results show that Vicker’s hardness and compressive residual stress will increase with the decrease of rake angle, clearance angle, cutting edge angle or minor cutting edge angle, surface roughness increases with an increase of rake angle or clearance angle and decreases with an increase of cutting edge angle or minor cutting edge angle.

Abstract: High strain rate superplastic (HSRS) bulging and cavitation behavior of a cold rolled Al-6Mg-0.3Sc sheet were investigated at the temperature of 798K and at the constant applied flow stress of 6.0MPa. The maximum effective strain of about 2.1 was obtained. The experimental results revealed that the cavity growth was essentially plastic - controlled. HSRS bulging limits of the sheet were further predicted based on the Marchiniak - Kuczynski model and a plastic damage approach. It is able to predict HSRS forming limits of the sheet in a reasonable agreement with the experimental findings even without assuming any initial geometrical defect.