INVESTIGATION OF THE STRUCTURE OF DIFFUSION LAYERS ON ARMCO-IRON DURING POWDER BOROCOPPERING

10.25712/ASTU.1811-1416.2023.04.014

Abstract

The paper presents the results of studies of diffusion layers obtained on ARMCO-iron samples in powder mixtures containing boron and copper. The aim was to study the effect of the copper content in the saturating mixture on the structure, structure and thickness of the diffusion layer. The method of conducting the experiment is described in detail: description of the compositions of the saturating mixture, boromedning modes, further metallographic studies and microhardness measurements. A comparative analysis of literature sources on the state and development of the situation with surface hardening at machine-building enterprises is carried out. As a result, diffusion layers with a thickness of 120 to 220 mm different in structure and structure, were obtained on ARMCO-iron samples. With a thickness of 120 mm the layer has a «classic» needle-like structure, and with a thickness of 220 mm the layer loses its needle-like structure and takes the form of a continuous layer with an adjacent feathery phase. An increase in the concentration of copper by 3 times (composition No. 2) compared with composition No. 1 had an effect on the distribution of microhardness. The difference between the highest values of microhardness is insignificant, it is 50 HV, but the further distribution has a smoother character, without sudden jumps or differences. It was found that an increase in the copper content in the saturating mixture contributes to an increase in the thickness of the diffusion layer and a change in the structure and structure of the layer. Copper also influences the microhardness distribution of the obtained diffusion layers. At the maximum concentration of copper in the composition of the saturating mixture, the microhardness has a smoother distribution, without sudden jumps and drops