Selection the measuring system for registering the metal parts temperature at microarc heating and its thermophysical analysis

Abstract

Measuring the temperature of metal parts during thermal and thermochemical treatment is necessary for the control of the correctness of the technological process. Currently, new methods of thermochemical processing of parts under high-energy conditions, such as microarc surface alloying, are proposed. Heating is carried out by the action of microarc discharges on the surface of parts immersed in coal powder when an electric current flows. It reduces the processing time from a few hours to a few minutes, but makes it difficult to measure the temperature, because heating occurs in dynamic mode. The aim of the work was to select a measuring system for recording the metal parts’ temperature during microarc heating, and the thermophysical analysis of the heating process. The S-type sensor was selected. The measuring system also includes a digital multimeter and a personal computer. The density of the electric current on the surface of the samples was 0.53 A/cm2 The registered heating curve consists of several stages. At the first stage the heating speed was about 8 °C/s. At the second stage it increases to 16 °C/s, but then decreases to 3.5 °C/s. Then the temperature increases monotonously with an average speed of 9 °C/s. At the fourth stage the sample temperature is stabilized at 1250 °C. The thermophysical process’ model of the heating metal parts under the influence of microarc discharges was proposed. The analysis showed that the calculated data coincide with the experimental data.