Исследование влияния технологических факторов на неопределенность результатов измерения теплопроводности методом лазерной вспышки

The estimation of the deviation in the measurements of thermal conductivity by the laser flash method for materials with different thermal conductivity coefficients, arising due to the presence of a graphite coating on the sample and the small thickness of the sample, is carried out. A computer model of the method was created in the Comsol Multiphysics software environment. For bulk samples with a graphite coating thickness of 20 μm, the deviation is 5.5 %. The thickness of bulk samples does not affect the measurement results. For materials with low thermal conductivity, a sharp increase in the deviation is observed, reaching 60%. For thermally conductive materials, the deviation is 16-18%. For thin samples less than 10 μm thick, the thickness of the graphite coating does not affect the measurement results. The decisive factor is the duration of the laser pulse.

FEATURES OF STRUCTURE FORMATION IN NI-C, AL-C AND NI-AL-C SYSTEMS UNDER HIGH-TEMPERATURE HEATING

The high-temperature treatment of powder mixtures of Ni-C, Al-C and Ni-Al-C (5% wt C (soot)) has been carried out up to the melting temperature of the metals. It was found that melt particles coagulate with the formation of spherical particles of Ni, Al, and the intermetallic compound NiAl, respectively. Ni particles are characterized by the almost perfect spherical shape and a multilayer graphite coating. NiAl particles have a thin graphene (graphite) coating.

Analysis of the Transient Contact Resistance of Composite Copper-Graphite Material Obtained Using Plasma Spraying Technology

The article is devoted to the analysis of the internal structure and properties of a copper-graphite coating applied to a copper electrode. The article provides a calculation of the transient contact resistance of electrodes with a coating obtained using plasma spraying technology. Copper-graphite powder with high arc resistance was used as a spraying substance. Coated electrodes were tested for erosion resistance by an arc at currents of several kiloamperes. The aim of the work is to determine the effect of the composition and internal structure of the coating on the transient processes in the contact gap.