METHOD FOR CREATING ANTI-DIFFUSION BARRIER ON SURFACE OF PLATES MADE OF THERMOELECTRIC MATERIALS BASED ON BISMUTH AND ANTIMONY CHALCOGENIDES

摘要

FIELD: thermoelectric instruments. ;SUBSTANCE: invention relates to thermoelectric instrumentation and can be used for chemical processing of plates before electrochemical deposition of metal coatings on the surface of plates made of thermoelectric materials. The achievement of the expected result is ensured due to the fact that the “Method for creating an anti-diffusion barrier on the surface of plates made of thermoelectric materials based on bismuth and antimony chalcogenides” includes chemical treatment of plates with solutions containing nitric and hydrochloric acids and electrochemical nickel plating of the surface of the plates. In this case, the chemical treatment is carried out in three stages: at the first stage, the chemical treatment of the plates is carried out in a solution of sodium hydroxide with a concentration of 10, wt. %. At the second stage, the chemical treatment of the plates is carried out at a temperature of 20-30°C by aqueous solutions of hydrochloric and nitric acids for one minute. And the third stage is also carried out with aqueous acid solutions at a temperature of 20-30°C for one minute, then electrochemical nickel plating is carried out in an electrolyte for nickel plating. In addition, the first stage of chemical treatment of plates is carried out in an ultrasonic bath with an ultrasound power equal to 60 W/cm2 at a temperature of 45°C for 5 minutes. And at the second stage, chemical treatment of plates with acid solutions is carried out at a volume ratio: water : hydrochloric acid : nitric acid, equal to 18:1:1, respectively, followed by washing in distilled water at a temperature of 18-20°C for one minute. Finally, the third stage of chemical treatment of the plates is carried out with solutions of hydrofluoric and nitric acids at a volume ratio: water : hydrofluoric acid : nitric acid, equal to 38:1:1, respectively, followed by washing in distilled water at a temperature of 18-20°C for 1 min. Then electrochemical nickel plating of plates made of thermoelectric material is carried out in an electrolysis bath with an electrolyte containing hydrochloric acid and nickel chloride in a volume ratio equal to 1:2.5 at a cathode current density of 0.4 A/dm2 for 5 minutes to obtain a nickel layer thickness of 10-15 mcm. ;EFFECT: increase in the adhesive properties of the surface layer of plates made of thermoelectric materials by creating an anti-diffusion barrier on it by chemical treatment of plates made of thermoelectric materials with ultrasound and step-by-step by solutions of various acids with an optimally matched ratio between them.;1 cl