Preparation And Diamond Ultra-precision Cutting Of Iron Nitride Materials

With the rapid development of the science and technology, for all kinds of high precision optical devices and high precision plane, curved surface or complex shape parts machining is urgent need. Ultra-precision diamond cutting technology with its good controllability, excellent cutting efficiency and other characteristics has become the machining precision machinery and optics of the most important methods. Steel because of its low cost and functional diversification is still the most widely used engineering materials, attracts attention of ultra-precision diamond cutting research. But because excessive tool wear occurs when steel alloys are machined by diamond tools, it is traditionally believed that diamond tool can not be used to cut steel material. This serious restricts the application of steel materials in the field of precision and ultra precision machining. If can solve the problem of cutting steel diamond produced serious wear effectively, it will bring about great economic and social benefits.This paper try to improve the diamond cutting of steel materials through nitriding, mainly deal with gas nitriding and heat treatment process of pure iron samples, so that a certain thickness of pure iron nitrogen compound layer and a diffusion layer consisting of different concentrations of nitrogen, then use diamond cutting lathe cutting the sample. The structural characterization and cutting performance of samples by means of x-ray diffraction (XRD), metallurgical Microscope, scanning electron microscope (SEM), white light interferometer, surface profile gauges and ultra-depth three-dimensional microscope. The main subject of the work and the results includes the following sections:(1) The thickness of compound layer of the pure iron (about 0.4mm thick) can be increased to varying degrees through the iron thin (about 0.4mm thick) for simple accumulation cycle nitriding, high and low temperature annealing cycle nitriding and nitriding cycle, then cutting the compound layer of this samples, the result is the density of the compound layer of the simple accumulation cycle nitriding is best and its surface is best excellent after cutting(Ra less than 6nm), the tool wear is significantly improved. So that we can know ε-Fe2-3N as a main component in the compound layer having a diamond machinability.(2) The pure iron (about 1.8mm thick) can form a thickness of compound layer and different concentrations of the nitrogen of the diffusion layer by step treatment of nitriding, annealing and quenching. The results of diamond cutting show that the low nitrogen content in the diffusion layer of the sample by nitriding is best(Ra about 6nm), furthermore the wear of diamond tools is lighter and the thickness of this layer is about 100 μm, this is suitable for diamond cutting.(3) Through calculation can plotted the curve of nitrogen concentration and the diffusion layer depth by gas nitriding at 550tyxy and three hours, so that we can estimate the nitrogen concentration at 0.285～0.323 at.% of the low nitrogen content in the diffusion layer is best for diamond cutting.