RESTORATION OF WORN DETAILS OF AGRICULTURAL MACHINERY WITH GALVANIC COATINGS
We have conducted experimental and analytical studies showing the relationship of constant and pulse forms of current sedimentation on the physico-chemical properties of chrome coatings: adhesion strength to the substrate, residual stress, fatigue life, elongation and contraction, yield stress, and endurance. We have shown the methods and modes of use of dilute electrolyte of chromium plating with organic additives, is capable of applying a chrome coating on parts of agricultural machines, surpassing the properties of the coatings obtained from electrolytes that are recommended by the GOST standards. The proposed hardening chemical-thermal coating technology for chromium in the manufacture and repairing of worn parts of agricultural machinery (rods of hydraulic cylinders, journals of crankshafts, spools, parts, gearboxes and transmissions, etc.), identifies the consumption of additives modifiers, proposed methods for their determination, confirmed by patents for inventions. The proposed technology of worn-out surfaces of parts of agricultural machinery of layer-block structure of the chromium coatings with improved properties. The influence of modifying organic additives on the structure of the intermediate surface film of colloidal trivalent chromium compounds, which in combination with the parameters of the bipolar pulse current allows you to specifically adjust the physical and mechanical properties of crystals of the deposited chromium layer with a grid of cracks, and without them for the required operating conditions of dry friction or oil environments, which increases the durability of the parts during use. The increase in yield, at the current 6-8 %, to 4 times reduces the degree of hydrogenation of the restored details, up to 3 times reduces internal friction, roughness, improves the limits of strength, toughness, elongation and contraction, increases corrosion resistance up to 3 times, obtained chromium coatings