CS214553B1 - The method of galvanic application of a functional layer resistant to abrasion - Google Patents

Abstract

The invention falls into the field of galvanic technology. It solves the problem of galvanic application - application of a functional layer resistant mainly to abrasion, characterized by the fact that a layer of thickness 0.02 to 0.04 mm is applied, preferably from a chromium-molybdenum alloy, secreted from a bath containing 150 to 250 kg, rn-^ chromium oxide, 30 to 75 kg., m of ammonium molybdate, 1.0 to 2.5 kg. -3 m of fluorosilicic acid or its salt and 0.6 to 1.0 kg.m of sulfuric acid or its salt at a temperature of 45 to 60 °0 and , ' 3 „ 3 —2 current density of 3.10 to 5»10 A m ·

Description

The present invention is in the field of electroplating. It relates to a method of galvanic deposition of a wear-resistant functional layer, characterized in that a thickness of 0.02 to 0.04 mm, preferably of chromium-molybdenum alloy, deposited from a bath containing 150 up to 250 kg, rn ^- 2 of chromium oxide, 30 to 75 kg, m of ammonium molybdate, 1.0 to 2.5 kg.

m of fluorosilicic acid or a salt thereof and 0.6 to 1.0 kg.m of sulfuric acid or a salt thereof at a temperature of 45 to 60 ° 0 and a.

214 553

The present invention relates to a method for the galvanic deposition of a wear-resistant functional layer on mutually moving contact surfaces of the components of the devices.

The surface of functional parts of components that are subject to friction and dynamic stress in operation, while operating under extreme conditions in terms of temperature or environmental aggressiveness, such as piston rings, pistons, valves, pins, functionally camshaft and crankshaft parts in internal combustion engines and compressors, parts of gearboxes such as shafts, gears and synchronous rings etc. have so far been produced in three ways. · In the first mode, the components were manufactured from pieces of refined material, which required the consumption of high-alloy materials. As a rule, large quantities of poorly machined material were required during machining, which was disadvantageous in terms of labor, power consumption, tools and machine equipment. In a second method, a layer of material of desired properties was welded onto the functional surfaces, and then the surface was machined to its final shape and dimensions. Even in this manner, the machining of the functional surfaces was laborious and expensive, in particular due to the uneven machining allowance and the properties of the weld deposit, in particular its surface layers. A disadvantage of this method was also the fact that an accurate and uniform deposition thickness cannot be maintained even after machining, as well as high residual stresses between the deposition and the base material. In the correct manner, a hard metal layer, most commonly chromium, was usually galvanically deposited on the functional surfaces of the components, usually in larger thicknesses, and the surface was subsequently machined to the required tolerances. The disadvantage of this method was the necessity to first deposit a thin layer of coating by a low-productivity technology, which in the following had to be laboriously worked, which created considerable conditions for surface damage during production. Even in the case of the possibility of deposition of a layer with an exact tolerance, there was a fundamental lack of abrasion-resistant chrome layers produced by the prior art, which consisted in their inability to maintain a lubricant film on the functional surface of the component required to reduce friction.

The above-mentioned deficiencies are substantially eliminated by the method of galvanic deposition of a wear-resistant functional layer, which consists in the fact that a layer of 0.02 to 0.04 mm, of chromium molybdenum, precipitated from a bath containing 150 to 250 kgm ^{- 'one} oxide of chromium, 30-75 kg ^ nT molybdežanu solution, 1.0 to 2.5 kg m "^ fluorokromičitej acid or a salt thereof and 0.6 to 1.0 kg of sulfuric acid or a salt thereof in 45 ° to 60 ° C; and a current density of 3.10 to 5.10 µm m ² .

The galvanic deposition of the functional layer according to the invention on a part having pre-adjusted dimensions of the parts with functional surfaces so as to have precise dimensions after metering eliminates the need for subsequent machining of the difficult-to-machine material. A thickness of 0.02 to 0.04 mm increases sufficiently uniform and ensures long-term protection prpti opotrebeniu. The puncture layer of the chromium-molybdenum alloy deposited from the bath of the above-mentioned composition and under the mentioned conditions has a hilly structure with rounded protrusions. This structure has not been achieved by the methods used hitherto. The hilly structure allows the lubricant layer to be maintained on the functional surface of the component. Another advantage is that when moving the parts, only the rounded projections of the surface interact with each other, which considerably limits the possibility of seizing the parts.

Example <1.

A 0.03 mm thick chrome-molybdenum alloy layer from a 200 gA bromine dioxide bath, 40 gA AH4 / gMoyOg4 was applied to the rings of the synhronizing cones for the gearbox of a passenger car. 41 ^ 0, and 10 g of Na ₂ Si PG as used and 0.8 gA of ^H2S ° 4th The plating conditions were as follows with a temperature of 48 ° C, a current density of 35 A / dm ² . The durability test results showed that after 200,000 function areas, there were no signs of wear.

Example 2

A 0.04 mm chrome-molybdenum alloy layer from the bearing bath described in Example 1 was applied to the gear-box teeth of the gearbox. The working conditions for the coating were subsequently temperature 55 ° C, current density 50 A / dm ² .

Claims (1)

OBJECT OF THE FINISH Method of galvanic application of a functional layer mainly resistant to abrasion, characterized in that the layer is applied to a depth of 0.02 to. 0,04 mm, of chromium-molybdenum alloy, excluded from a bath containing 150 to 250 kg m ^{-3 of} chromium oxide, 30 to 75 kg m ^{3 of} ammonium molybdate, 1,0 to 2,5 kg m ³ of fluorocremioic acid or its salt and 0.6 to 1.0 kg m ^"3 sulfuric acid or a salt thereof at 45 to 60 ° C and a current density of ³ to 3,1O 5,1O ³ and m ^'2. Printed works, plant 75, Mlada Boleslav Price: 2,4 0 Kčs