AU6138300A

AU6138300A - Coating method

Info

Publication number: AU6138300A
Application number: AU61383/00A
Authority: AU
Inventors: Evgueni Kniazev
Original assignee: Hpc High Performance Coating Oberflachenbehandlungs GmbH
Current assignee: HPC HIGH PERFORMANCE COATING OBERFLACHENBEHANDLUNGS-GMBH
Priority date: 1999-06-29
Filing date: 2000-06-28
Publication date: 2001-01-22
Also published as: EP1200640B1; PT1200640E; ZA200200439B; ATE234372T1; ES2193093T3; HRP20010957A2; WO2001000425A1; WO2001002623A1; RU2147524C1; EP1200640A1; CN1359429A; DE50001459D1; HUP0201790A2

Abstract

The invention relates to a method for the fabrication of products to improve the working characteristics of a product. Said method is characterized in that the basic treatment of an aqueous suspension of an ultradispersed diamondlike carbon cluster is carried out in an aqueous sulfuric acid or hydrochloric acid solution before applying the coating and in that the acids are subsequently washed off in distilled water. The technical result of said method is an improved operating characteristic curve of the product using smaller amounts of the costly product UDA.

Description

-1 Coating Method The invention relates to a method of coating products, in particular decorative veneers, items of jewellery, clocks, tools, etc.. A known method of making products consists in producing a workpiece and then applying a coating to the surface of the workpiece from the electrolyte suspension containing ultra-dispersed diamond-like carbon clusters (see Schebalin A.I., Gubarewitsch W.D., Besedin W.I., Priwalko Ju. N. in Diamant-Chrom-Kompositionsschicht, Explosion, Schlag, Schutz, 1987, 17 th edition, p. 111-112, analogy and prototype). The known method of making products does not take account of the fact that the presence of particles of the ultra-dispersed diamond-like carbon clusters (UDA) from chemical groups of predominantly acid origin on the surface causes the particles of the disperse phase in the electro lytes to behave in a specific way at different pH values. Consequently, the particles of the UDA in acid medium (pH < 7), which is typical of the majority of electrolytes in chrome plating, nickel plating and a few others, receive a negative charge, which impairs their functional capacity on the surface of the cathode, which is also negatively charged. As a result, occlusion of the par ticles in the coating is negligible. However, it is the nature of the surface of the particles in the UDA which promotes their functional capacity on the cathode. It is crucial to ensure that the surface of the carbon particles (in the same way as cations) is maintained in the state of the H-form. However, analysis of commercial batches of products available on the market for UDA has shown that the product is in what is referred to as the "salt form". In technical terms, the intention of this method is to improve the working characteristics of the product whilst using smaller quantities of the expensive UDA product. This is achieved due to the fact that the main treatment of aqueously suspending the ultra dispersed diamond-like carbon clusters in an aqueous suspension of sulphuric or hydrochloric acid and then removing the acids in distilled water and the post-treatment by means of a cationi cally active substance, in order to reduce the volume capacity and re-charge the surface of the -2 particles in the electrolyte, take place prior to coating. Substances with a tertiary or quaternary ammonium base are used as the cationically active sub stance. As an electrolyte suspension, the electrolytes used are based on hexavalent chromium, nickel, iron, gold and its alloys with cobalt, nickel, silver and copper, and copper. The essence of the method for making products will be explained in more detail below. Workpieces were prepared, e.g. in the form of a cylinder of IIIX 15 steel with a hardness HV = 8.5+0.2 GpA. Coatings were applied to the workpieces in a thickness of at least 50 gm from dif ferent electrolytes, in particular electrolytes containing the ultra-dispersed diamond-like carbon clusters (UDA). Coating was preceded by the main treatment of suspending the ultra-dispersed diamond-like car bon clusters in the aqueous sulphuric or hydrochloric acid solution and then washing out the ac ids in distilled water and the post-treatment with the cationically active substance to reduce the volume capacity and re-charge the surface of the particles of the electrolyte. Substances with a tertiary or quaternary ammonium base were used as said substance. Electrolytes on a base of hexavalent chromium, nickel, iron, gold and copper were used as the electrolyte. The abrasion resistance of the coatings was measured on a system which applies friction by means of a hardened steel or greasing based on the "cylinder with crossing axes" design. The abrasion resistance was determined as a value correlated to the quantity of abraded substance for the specified duration of the tests (the length of the abrasion path) and the friction load applied (for different types of coating, see Table, the absolute friction load for chromium and iron was 15 N, for nickel 10 N, for copper and gold 5N). The sliding speed was 0.78 m/s and the length of the friction path was 140 m. Antibodies were X 12M steel with HRC 3 = 60 =1, R 2 =0.25-0.32 gm. The microhardness of the coatings was measured by a DMT-3 device under a load of 100g and 50g.

-3 Accordingly, the products made by the specified method were found to have better abrasion re sistance and consequently were of higher quality. In another example, the decorative protective coating is applied in a thickness of 5 gm of a gold cobalt alloy with a fineness of 985 to the body of a man's wrist watch made from brass C59-1 instead of the usual coating of electrolyte, consisting of gold in the form of a cyanide complex in a quantity of 6.5 g/l, cobalt in the sulphate form in a quantity of lg/l, tri-substituted aqueous 2-x potassium citrate in a quantity of 60 g/l and 3g/l of -A-Trilon admixed with "Limeda 30-12" and UDAtreated = 10 g/l to produce a sheen, whilst the electrolyte temperature was 40'C, the current density 0.6 A/dm 2 and the pH value 4.5. The abrasion resistance of the coatings was tested on a drum system with an abrasive agent in the form of cylindrical grains of rubber with glass, being 8 mm in diameter and 10 mm in length (sample tested every 10 minutes). The additional test for exposure of the base (brass) was con ducted using a 10%-strength chlorine-copper solution (according to the redness of the base). A visual inspection was made under a MBC-2 microscope with 12-times magnification. The tests were continued until the base was exposed at sharp angles of the watch links. The results of the tests showed the abrasion resistance of the coating with the treated cluster to be 1.7 times better than the initial cluster. The abrasion resistance of the coating with the initial cluster is 2 times higher than the abrasion resistance of the gold-cobalt coating without UDA. The coating hardness was therefore increased from 2.5 GPa (UDAinitial) to 3.2 GPa (UDAtreated). The invention therefore improves the working characteristics of the products. Clearly, the coating method proposed by the invention may also be used for other workpieces, in particular the surfaces thereof. It is possible to coat both all-metal and non-metal workpieces which have been electrolytically treated in acids. For example, the method may be used for spectacle frames, household articles, plastics or similar. Optionally, an additional pre-treatment might be necessary, e.g. in the case of plastics, in order to precipitate a conductive layer onto the respective articles.

-4 Industrial application: The invention may be used for decorative veneers, articles of jewellery, watches and tools, amongst others. Coating, coat- Composition of the Abrasion sur- Factor of increase Hardness, GPa ing method electrolyte face, mm 3 in hardness 1 2 3 4 5 Chromium CrO 3 -250 g/l;

H

2

SO

4 -2.5 gil; 50 A/din 2 (pH 1) 55-57 0 C UDAinitiar15 g/l 0.18 x 10-2 1.0 9.5 UDAtreated-15 g/l 0.87 x 10- 3 2.0 9.8 UDAtreated-10 g/l 0.13 x 102 1.4 9.8 Cr03-250 g/l;

K

2 SiF 6 -18 g/l; SrSO 4 -6 g/l; UDAinitiar15 g/l 0.15 x 10-2 1.0 10.5 same with UDA treated-1 5 g/l 0.92 x 10~ 3 1.6 12 same with UDA treated- 8 g/l 0.11 X 10-2 1.4 11.5 Nickel NiSO 4 -270 g/l; NiCl-30 g/l; 5 A/ dm2 H 3

BO

3 -30g/l; (pH=4.5) 65 0 C +UDAinitia-20g/l 0.7 x 101 1.0 2.7 same +UDAtreated-20g/l 0.29 x 101 2.4 3.8 same +UDAtreated-1Og/l 0.52 x 10-' 1.34 not measured -5 Copper CuSO 4 -45 g/l; Na 4

P

2 0 7 -160 g/l; 1.5 A/ dm 2 Na 2

HPO

4 -90 g/l; (pH= 8

.

5 ) + UDAinitiar8 g/l + UDAtreated-8g/l Gold Au in the form of the cyanide com plex 0.6 A/ dm2 10 g/l; citric acid 35 g/l; 40 0 C Tri-substituted potassium citrate 35 g/l; Sheen agent "Limeda 3C-12" lg/l; + UDAinitia-l0g/l 0.19 x 10-2 1.0 1.89 + UDAtreated-10gl 0.32 x 10-2 1.7 2.42 Iron FeSO 4 -400 g/l; Al(SO 4

)

3 -100 g/l; 5 A/ dm2 (pH= 3 ) 60 0 C + UDAinitia-0g/l 0.31 x 10-1 1.0 4.2 + UDAtreated-10g/l 0.21 x 10~1 1.7 4.9

Claims

1. Method of coating objects with a coating from an electrolyte-suspension containing ultra dispersed diamond-like carbon clusters, characterised in that the main treatment with aqueous suspension of the ultra-dispersed diamond-like carbon clusters in aqueous sulphuric or hydro chloric acid solution and then washing out the acids in distilled water and the post-treatment by means of a cationically active substance to reduce the volume capacity and re-charge the surface of the particles in the electrolyte take place prior to coating.

2. Method as claimed in claim 1, characterised in that substances with a tertiary or quater nary ammonium base are used as the cationically active substance.

3. Method as claimed in claims 1 and 2, characterised in that electrolytes with a base of hexavalent chromium, nickel, iron, gold and its alloys with cobalt, silver and copper, and copper are used as an electrolyte suspension.