METHOD OF DETERMINING DIFFUSION COEFFICIENT IN POWDER MATERIALS AND METHOD OF DETERMINING THICKNESS AND INDEX OF COATING INTEGRITY ON PARTICLES OF POWDER MATERIALS Russian patent published in 2014 - IPC G01N13/00 

FIELD: chemistry.

SUBSTANCE: in a method of diffusion coefficient determination electroconductivity of a material in an initial state is measured to determine initial content of a diffusant in a coating on its particles. After that, the material in bulk is subjected to diffusion annealing, cooled, and electroconductivity is measured to determine the changed content of the diffusant in the coating. Measurement of the material electroconductivity before and after annealing is carried out with a different degree of compression, also, before and after annealing determined are the coating thickness and an index of its integrity, which are taken into account in measuring the change of the diffusant content in the coating with a constant value of its concentration, a diffusion coefficient is determined by an expression, obtained by solution of the Fick equation. The said sequence of actions is repeated at different temperatures of the material annealing to obtain a temperature dependence of the diffusion coefficient, which is used in accordance with the Arrhenius law to determine its constant parameters: pre-exponential factor and activation energy. In realisation of the method of determining the thickness and index of the coating integrity the material sample is compressed, its electroconductivity is measured for different degrees of compression, electroconductivity of the material in a nonporous state is determined. In addition, a specific surface of the material and electroconductivity of the material without coating are measured, an average statistical coordination number of conducting contacts of particles is determined. After that, a relative area of projection of an unscreened by coating contact surface of material particles in a nonporous state, characterising the coating integrity and the coating thickness, is calculated.

EFFECT: increased accuracy and reliability of determination, method simplification, and extension of the application area.

2 cl, 7 dwg