SU1689431A1 - Method of activating metal surface before chemical nickel plating - Google Patents

Description

The invention relates to the preparation of the surface of metal products before chemical nickel plating, mainly, products, including a combination

aluminum and iron, and can be used in mechanical engineering for surface hardening of parts used in conditions of corrosion and mechanical interaction with the external environment. The purpose of the invention is to increase the adhesion of the coating. The method of activation of metal products before chemical nickel plating includes treatment with a solution containing, g / l: sodium hypophosphite 0.1-400: the salt of a rare-earth element (in terms of metal) is 0.025-1.50, at a temperature of 3080 ° С, pH of solution 6, 0-7.0, for 0.155.0 minutes As the salt of a rare-earth element, salts of lanthanum, cerium, neodymium, yttrium are used. The use of a solution containing sodium hypophosphite and a salt of a rare-earth element, with the above treatment parameters, provides an increase in the adhesion of the coating to the base, including the iron-aluminum combination. 1 hp f-ly, 1 tab.

The invention relates to the preparation of the surface of metal products before chemical nickel plating, mainly of products including a combination of aluminum-iron metal coatings, and can be used in mechanical engineering for surface hardening of parts operated under corrosion and mechanical stress conditions with the external environment.

The purpose of the invention is to increase the adhesion of the coating.

The method of activation of metal products, mainly involving a combination of aluminum and iron, consists in processing a solution containing, g / l: sodium hypophosphite 0.1-400; salt of rare earth element (in terms of element) 0.025-1.5. As a rare-earth element, lanthanum, cerium, neodymium, yttrium (La, Ce,, Y) are used.

Rare-earth elements can be introduced in the form of compounds such as 1_a-P, where P is an organic or inorganic radical (for example, 50а ² ; СНзСОО ^- etc.).

Activation is as follows. Atomic hydrogen released in the oxidation process of the hypophosphite ion

1689431 A1

1689431

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interact with cations of rare-earth elements with the formation of hydrides on the metal surface. These compounds, with their relative stability in neutral media, are actively decomposed in acidic solutions with release of atomic hydrogen. Thus, atomic hydrogen enriches the layer of the solution in contact with the metal, which at the initial moment contributes to the intensive deposition of nickel.

In this case, the effect of the proposed group of rare-earth elements is almost the same and the choice of a particular compound is dictated by its availability.

The quality of processing is reliably assessed visually, by the presence of a uniform dark gray film. In case of obtaining defective hydride layers, it is possible to remove them in dilute acid solutions and reapply.

The boundary values of the activation factors are established by the condition for the formation of a continuous hydride film.

Example. The proposed method conducts the simultaneous activation of the surface of mechanically bonded steel (steel 45) and aluminum (alloy D16T1) specimens 30x70 mm in size, previously cleaned of grease in alkaline solution and oxide films in an aqueous solution of phosphoric acid (200 g / l), followed by their loading into the solution for chemical precipitation

Nickel composition, g / l:

Nickel sulphate 21

Sodium hypophosphite 24

Sodium acetate 10

Maleic anhydride 1.5

The deposition process is carried out at 90 ± 1 ° C and pH 4.8-0.2.

The effectiveness of the proposed method is evaluated by the quality of adhesion of the nickel coating to the base metals by thermal cycling: heating 400 ° C and cooling in water at 25 ° C.

The table shows the dependences of the quality of nickel coatings on the concentrations of the components, the acidity of the solution, the temperature and the treatment time in the activation solution containing cerium sulfate Ce (5О4) g · 4HO, lanthanum acetate 1_a (C, H3COO) s x 1.5PgO, neodymium sulfate N62 (504) 3 x 8HO, yttrium sulphate Ug (ZO4) 3 · 8 · 2θ.

The boundary values of the parameters are given in experiments 2, 4, 7, and 9, and the optimal ones in experiments 3 and 8.

Control tests of coatings applied by a known method, carried out with the activation surface from a solution of the composition, g / l:

Sodium hypophosphite 25 Nickel sulfate 25 Ammonium citrate 50 at a temperature of 90 C, time 1 min and

acidity pH 9.0. Nickel coating on steel 45 peels off after one, and on alloy D16T1 - after two thermal cycles.

The proposed method of activation allows to increase the adhesion properties of a chemically deposited nickel coating on steel 45 to 3, and on alloy D16T1 up to 3-4 thermal cycles.

Claims (1)

Claim 1. The method of activating the surface of metal products before chemical nickel plating, mainly of products including a combination of aluminum and iron, by treating sodium hypophosphite in a heated solution containing a metal salt, characterized in that, in order to increase the adhesion of the coating, the sodium hypophosphite solution used for processing contains as a metal salt, a salt of a rare-earth element in the following ratio of components, g / l: Sodium hypophosphite 0.1-400 Salt of rare earth element (in terms of metal) 0.025-1.50 and the treatment process is carried out at a temperature of 30 ~ 80 ° C, pH of the solution is 6.0-7.0, for 0.15-5.0 minutes. 2, the method according to claim 1, deviating from the fact that a salt of lanthanum, cerium, neodymium, yttrium is used as the salt of the rare-earth element. five 1689431 6 The composition of the rare earth salt metal Main material Οΐ-ЫТ 8 RZSTPSrZ with this salt Soderhonns nst’Ronechts> 8 and technological geinem Sodium hypophosphite NlN ₂ PO _g P ₂ O, g / l The salt content of rare-salt. metal, g / l Temperature, * С g Roemp, min KNSLSP "OST, RF four 2 3 four five 6 7 δ Nolichesyao CYCLOP DP ruiiennch 3 Constipation ZLOMZNI8 REST8SRRL Sulphate cerium Steel 45 one 2 3 four five Also Apsmicia woven Λ16Τ1 AT 7 th 3 ten UNSUSNONISGL lanthanum Steel 45 / one 2 s four five That willows AgkpichieVMY SPLY L16T1 6 7 6 3 ten Sulphate neodymium Steel 45 one 2 3 four five Sulphate neodymium Agkminkee alloy L16T1 6 7 0 9 ten Sulphate yttrium Steel 45 one 2 s four five Ίο my Agkpnniyevyi spgaa L16T1 6 7 b 9 ten 425.0 400.0 25.0 0.1 0.075 425.0 400.0 25.0 0.1 0.075 425.0 400.0 25.0 0.1 0.075 425.0 400.0 25.0 0.1 0.075 425.0 400.0 25.0 0.1 0.075 425.0 4110.0 25.0 oh 1 0.075 425.0 400.0 25.0 0.1 0.075 425.0 400.0 25.0 0.1 0.075 1.75 1.50 1,125 0.025 0.02 1.75 1.50 1.125 0.025 0.02 1.73 1.50 1.125 0.025 0.02 1.75 1.50 1.125 0.025 0.02 1.75 1.50 1.125 0.025 0.02 1.75, 1.50 · 1.25 0.025 0.02 1.75 1.50 1.125 0.025 0.02 1.75 \50 1,125 0.023 0.02 6.0 eo 1, o 6.7 3 30 5.0 7.0 2 Lack of high-hea reactions Self-cultivating plant - 33 6.15 5.0 2 52 1.0 6.2 four 53 5.0 7.0 3 Ptsutstrne chemical reactions Sa: ‘. Pgailloechnp rlstegra - C, 15 Bb P 35 '1.0 5.0 3 50 5.5 7.0 3 PTSUTSTONO CHIINIRTS reactions Sgn.ppapgk'nya chst st on? that - 33 0.15 5.5 2 50 1.0 6,6 3 50 5.0 7.0 3 Ogsutstone chemical reactions * Self-decomposition - 30 0.15 6.5 3 60 1-5 6.7 3 30 '5.0 7.0 3 P'SUTSTRIO CHEMICAL reactions Self decomposition of organic matter - 30 0.15 6.5 3 50 1 0 0.7 four ου Р, 0 7.0 3 No chemical reactions Self-caretaker 30 0.15 6.0 2 03 ’. С 6.3 3 30’ з 0 7.0 2 No chemical reaction Self-decomposition opstoopa 30 0.15 6.0 2 60 1.0 6.3 · 3 50 5.0 7.0 3 No chemical reaction