CN105063676A - Method for electroplating hard chromium by using trivalent chromium - Google Patents

Abstract

The invention relates to a method for electroplating hard chromium by using trivalent chromium and aims to solve the problems that the existing hexavalent chromium causes pollution and a trivalent chromium electroplated layer is thin. According to the method, an electrode is dipped in a solution containing iridium and ruthenium and is sintered to form a surface-coated metal titanium plate electroplated anode; a direct-current power supply is adopted for supplying power; an trivalent chromium electroplating solution comprises the following components by content: main salts, complexing agents, catalysts, a buffering agent, conductive salts, other substances and the balance water, wherein the main salts are chromium sulfate and chromic chloride; the complexing agents are tartaric acid and diethylenetriamine, the catalysts are potassium bromide and potassium fluoride; the buffering agent is a boric acid-sodium borate system; the conductive salts are sodium sulfate and sodium chloride; the other substances include perfluorinated polyether pyrazinecarboxamide, glycerol, cane sugar and lauryl dimethyl glycine betaine; the PH value of the electroplating solution is controlled to be within 1.5 to 2.2 and is regulated by sulfuric acid and sodium carbonate. According to the method disclosed by the invention, the trivalent chromium is used as the main salt; organic acid and salt thereof are used as the complexing agents; halide and organic fluoride are used as the catalysts; a chromium coating which is 40 micrometers thick can be formed on a steel and iron work piece, and the micro-hardness HV is larger than or equal to 850.

Description

A kind of method of trivalent chromium plating hard chrome

Technical field:

The present invention relates to a kind of method of trivalent chromium plating hard chrome, be specifically related to a kind of chrome-plating method that can form wear-resisting thickness coating, belong to field of electroplating.

Background technology:

At present, in the electro-plating method of thickness coating hard chrome plating (microhardness HV is greater than 850, and thickness of coating is more than 20 μm), usually use the electro-plating method of sexavalence chromic salts, also have the electro-plating method adopting chromic salt.

Adopt sexavalence chromic salts as the electro-plating method of the main component of electroplate liquid, chromic salts used is chromium trioxide (chromic anhydride CrO ₃), this electro-plating method can obtain continuous, fine and close thick chromium coating at piece surface.This method current efficiency low (20%), electroplating process needs heating, there is chromic heavy metal pollution problem in three waste discharge.Sexavalent chrome is without special environmental protection treatment measure process, can not the nontoxic material of self-assembling formation, can form activated source of pollution for a long time in natural water body and soil, being carcinogenic, the clastogenic material that international medical community confirms, is the important control ion of heavy metal contamination.

Adopt the electro-plating method of chromic salt, with vitriol or muriate for main salt, coordinate the additives such as different complexing agents, conducting salt, buffer reagent, electroplate in acid condition.But the coating generated is thinner, usually can form the coating of continous-stable within 10 μm.When thickness of coating is more than 10 μm, coating can not form thick layer, or quality instability produces peeling, comes off, the defect such as hole.

The weak point that the method for electrodeposited chromium hard chrome exists at present is in sum that the plating of sexavalence chromic salts exists serious heavy metal problem of environmental pollution.Chromic salt plating Problems existing can not be formed not have chromium coating that is defective, stable, that have reliable thickness.

Summary of the invention:

The present invention is a kind of with the method for the trivalent chromium trivalent chromium plating hard chrome that is main salt by providing, solve current hexavalent chromium plating heavy metal pollution problem and trivalent chromium plating coating can not form thickness coating, or the problem of the defect such as quality instability produces peeling, comes off, hole.

The present invention is realized by following technical scheme:

A kind of method of trivalent chromium plating hard chrome:

Electrode is with through forming the metallic titanium plate DAS of top coat as galvanic anode containing iridium, the solution impregnation of ruthenium and sintering processes;

Power supply direct supply, current density 10dm ²~ 50A/dm ²;

Plating working temperature, 30 DEG C ~ 60 DEG C;

The component of trivalent chromium plating solution and content are:

Main salt: chromium sulphate and chromium chloride, calculating chromium sulphate than chromium chloride by content of chromium ion is 3: 1, and in solution, the content of trivalent chromic ion is 17g/L ~ 33g/L;

Complexing agent: tartrate 10g/L ~ 60g/L, diethylenetriamine 5g/L ~ 30g/L;

Catalyzer: Potassium Bromide and Potassium monofluoride, its ratio is 1: 2,5g/L ~ 10g/L;

Buffer reagent: boric acid-sodium borate system, 120g/L ~ 180g/L;

Conducting salt: sodium sulfate and sodium-chlor, calculating sodium sulfate than sodium-chlor by sodium ions content is 3: 1, and add-on is 30g/L ~ 90g/L;

Other material: PFPE carboxylic acid amine salt 0g/L ~ 18g/L, glycerine 0g/L ~ 8g/L, sucrose 0g/L ~ 20g/L, Empigen 0g/L ~ 12g/L, all the other are water;

Control electroplate liquid pH value between 1.5 ~ 2.2, regulate pH value with sulfuric acid and sodium carbonate;

The compound method of trivalent chromium plating solution: first the water of 1/2nd of metering is joined in container, add successively and become owner of salt, complexing agent, catalyzer, buffer reagent, conducting salt, rear a kind of material is added again after front a kind of substance dissolves, the water of 1/3rd is joined in another container, add PFPE carboxylic acid amine salt successively, glycerine, Empigen, sucrose, rear a kind of material is added again after front a kind of material solvent, by two kinds of solution mixing, regulate pH value between 1.5 ~ 2.2 with sulfuric acid and sodium carbonate, variable is supplemented to water, trivalent chromium plating solution has configured.

The invention provides a kind of Cr-plating Bath, with trivalent chromium for main salt, organic acid and salt thereof are complexing agent, halogenide and organic fluoride are catalyzer, can control the buffer system of pH value between 1.5 ~ 2.2 and do buffer reagent, inorganic salt are conducting salt, and other material is the compositing formulas such as additive.Plating anode material is selected through forming the metallic titanium plate of top coat as galvanic anode containing iridium, the solution impregnation of ruthenium and sintering processes.Power acquisition direct current electrode position power supply.Iron and steel parts is through conventional oil removing and activation treatment, electroplate under normal temperature condition, control the significant parameter of electroplating process, on iron and steel parts obtain continuous, fine and close, complete, with matrix metal in conjunction with good thick chromium coating, chromium coating thickness reaches 40 μm, microhardness (HV >=850).

Embodiment:

Embodiment 1:

The compound method of electroplate liquid, first the water of 1/2nd of metering is joined in container, add successively and become owner of salt with trivalent chromic ion content meter 33g/L, complexing agent (tartrate 60g/L, diethylenetriamine 5g/L), catalyzer 5g/L, buffer reagent (boric acid 120g/L), conducting salt 90g/L, add rear a kind of material again after front a kind of material solvent.The water of 1/3rd is joined in another container, add PFPE carboxylic acid amine salt 6g/L, glycerine 4g/L, Empigen 12g/L, sucrose 20g/L successively, after front a kind of material solvent, add rear a kind of material again.By two kinds of solution mixing, regulate between pH value 1.5 ~ 2.2 with sulfuric acid and sodium carbonate, be supplemented to variable with water, trivalent chromium plating solution has configured.

Electrode is with through forming the metallic titanium plate DSA of top coat as galvanic anode containing iridium, the solution impregnation of ruthenium and sintering processes.

Power supply direct supply, current density 20 ± 5A/dm ².

Plating working temperature, 45 ± 5 DEG C.

Make sample with Q235 steel plate (150 × 100 × 3), through operations such as polishing-oil removing-washing-activation-washing-plating-washings, plating 30min thickness can reach 50 μm, and hardness reaches HV=850.

Embodiment 2:

The compound method of electroplate liquid, first the water of 1/2nd of metering is joined in container, add successively and become owner of salt with trivalent chromic ion content meter 17g/L, complexing agent (tartrate 10g/L, diethylenetriamine 30g/L), catalyzer 10g/L, buffer reagent (boric acid 180g/L), conducting salt 30g/L, add rear a kind of material again after front a kind of material solvent.The water of 1/3rd is joined in another container, add PFPE carboxylic acid amine salt 18g/L, glycerine 6g/L, Empigen 3g/L, sucrose 10g/L successively, after front a kind of material solvent, add rear a kind of material again.By two kinds of solution mixing, regulate between pH value 1.5 ~ 2.2 with sulfuric acid and sodium carbonate, be supplemented to variable with water, trivalent chromium plating solution has configured.

Electrode is with through forming the metallic titanium plate DSA of top coat as galvanic anode containing iridium, the solution impregnation of ruthenium and sintering processes.

Power supply direct supply, current density 40 ± 5A/dm ².

Plating working temperature, 40 ± 5 DEG C.

Use 20Cr ₂ni ₄axle (Φ 100 × 150) makes sample, and through operations such as polishing-oil removing-washing-activation-washing-plating-washings, plating 45min thickness can reach 80 μm, and hardness reaches HV=880.

Claims (1)

1. a method for trivalent chromium plating hard chrome, is characterized in that: electrode is through forming the metallic titanium plate DAS of top coat as galvanic anode containing iridium, the solution impregnation of ruthenium and sintering processes;

Power supply direct supply, current density 10dm ²~ 50A/dm ²;

Plating working temperature, 30 DEG C ~ 60 DEG C;

The component of trivalent chromium plating solution and content are:

Main salt: chromium sulphate and chromium chloride, calculating chromium sulphate than chromium chloride by content of chromium ion is 3: 1, and in solution, the content of trivalent chromic ion is 17g/L ~ 33g/L;

Complexing agent: tartrate 10g/L ~ 60g/L, diethylenetriamine 5g/L ~ 30g/L;

Catalyzer: Potassium Bromide and Potassium monofluoride, its ratio is 1: 2,5g/L ~ 10g/L;

Buffer reagent: boric acid-sodium borate system, 120g/L ~ 180g/L;

Conducting salt: sodium sulfate and sodium-chlor, calculating sodium sulfate than sodium-chlor by sodium ions content is 3: 1, and add-on is 30g/L ~ 90g/L;

Other material: PFPE carboxylic acid amine salt 0g/L ~ 18g/L, glycerine 0g/L ~ 8g/L, sucrose 0g/L ~ 20g/L, Empigen 0g/L ~ 12g/L, all the other are water;

Control electroplate liquid pH value between 1.5 ~ 2.2, regulate pH value with sulfuric acid and sodium carbonate;

The compound method of trivalent chromium plating solution: first the water of 1/2nd of metering is joined in container, add successively and become owner of salt, complexing agent, catalyzer, buffer reagent, conducting salt, rear a kind of material is added again after front a kind of substance dissolves, the water of 1/3rd is joined in another container, add PFPE carboxylic acid amine salt successively, glycerine, Empigen, sucrose, rear a kind of material is added again after front a kind of material solvent, by two kinds of solution mixing, regulate pH value between 1.5 ~ 2.2 with sulfuric acid and sodium carbonate, variable is supplemented to water, trivalent chromium plating solution has configured.