No abstract

Peculiarities in the contact surfaces formation and material transfer at micro-scratching and grinding of refractory metals are investigated. There is shown a connection of metal quantity transferred to the area of crystal wear, a degree of ground surface charging with silicon carbide crystals and wear of an abrasive tool with the electron structure of atoms in refractory metals. It is defined, that the intensity of metal transfer in a crystal surface layer decreases with the increase of a principle quantum number of metal valence electrons. According to the intensity of the interaction silicon carbide during grinding and micro-cutting the refractory metals are classified into adhesion-active metals of IVB, VB sub-groups and inert metals of VIB subgroup of the Periodic Table.

The article summarizes the results of microscopic and x-ray spectral studies of objects embedded in the surface layer of a nickel alloy after grinding with a wheel of cubic boron nitride (CBN) on a ceramic bond. In the introduction, the authors analyzes the results of research on the use of CBN as an abrasive material. Unlike silicon carbide wheels, CBN tools are a more complex and multi-component structure, which has a significant impact on the self-sharpening of the abrasive tool and the transfer of material. The purpose of this article is to detect and identify the wear products of a CBN grinding wheel on the treated surface of a nickel alloy. As a result of studying the morphology of the alloy surface after grinding with CBN wheels, foreign objects embedded in the metal were detected with a scanning two-beam electron microscope. The chemical composition of the objects was studied by x-ray spectral microanalysis. Based on the obtained spectrograms, the objects were divided into three groups, including peaks of x-ray characteristic radiation: boron and nitrogen characteristic of CBN grains; aluminum and oxygen characteristic of corundum; oxygen, silicon, aluminum, and some elements characteristic of a ceramic bond. Tables of the chemical composition of the studied objects are provided. Conclusions. The transfer of CBN grinding whee wear products from to the treated surface is experimentally proved.

The article describes features of the wear site morphology formation during micro-scratching of a titanium alloy by a silicon carbide crystal in comparison with a corundum crystal. The initial shape of the crystal top and the rate of micro-scratching were assumed to be constant. No lubricating or cooling process media were used. External factors: micro-scratch depth and cutting path length. The chemical composition of wear sites was studied using micro-x-ray spectral analysis. The content of chemical elements in the surface layer of silicon carbide and adhered metal was studied at separate points and by area scanning. The accelerating voltage of the excitation electrons was changed in the range from 5 to 20 kV. The concentration of chemical elements on the surface of the wear site was determined immediately after micro-scratching and after removing the adhered metal by etching. The regularities of changes in the concentration of chemical elements depending on the accelerating voltage of the excitation electrons were determined.

The study of the surface of silicon carbide after grinding niobium was carried out on a Versa 3D electronic microscope. It is shown that as a result of the grinding, traces of the grinding wheel material are formed on the treated surface, and the ground material itself is prone to adhesion to the grinding wheel. As a result of cohesive interaction, the metal adhering to the grinding wheel is transferred, and vice versa. And, as a result of adhesion-fatigue processes, mechanical action, there is a hanging wear of the grinding wheel and the indentation of individual crystals of silicon carbide into the surface of the metal being processed. This article examines such features of the behavior of niobium, when grinding it with silicon wheels and is considered from the standpoint of the electronic structure of the metal atom.