The invention discloses a method for chroming by using trivalent chromium A plating liquid is prepared from the following raw materials: 125-120 g/L of chromic chloride, 110-130 g/L of urea, 25-30 g/L of ammonium chloride, 9-10 g/L of boric acid, 85-95 g/L of methanoic acid, 200ml/L of carbinol, 25-35 g/L of sodium chloride and 005-02 g/L of thioformamide The method comprises the steps of: during electroplating, electrolyzing for 24 hours by adopting the plating liquid, regulating the pH value to be 165-175, cleaning a part to be electroplated, then feeding into a plating groove in the electrifying state at the temperature of 20-40 DEG C, keeping constant potential of -35V to ensure that a cladding material reaches a specified thickness, fishing out, and drying by hot air The invention has the advantages that complex ions formed by trivalent chromium and a ligand are completely depolymerized by using the thioformamide, the plating liquid is stable, the deposition speed is high, the generation of hydroxyl polymers can be inhibited when the pH value raises, and an electroplated chrome coating is in a stainless steel ground color and has better corrosion resistance and abrasive resistance

Method for chroming by using trivalent chromium

The invention discloses trivalent chromium electroplate liquid and a preparing method thereof. The trivalent chromium electroplate liquid comprises, by concentration, 0.1-0.15 mol/L of chromium sulfate, 0.25-0.35 mol/L of sodium gluconate, 0.8-1 mol/L of citric acid, 0.1-0.15 mol/L of aluminum sulfate, 0.002-0.004 mol/L of dodecyl sodium gluconate, 0.4-0.8 mol/L of a complexing agent, 15-20 mol/L of a stabilizer and the balanced solvent water. The stabilizer is a water solution which is formed by 2-3 mol/L of methyl alcohol, 2-3 mol/L of sodium sulfite and 1-2 mol/L of ferrous sulfate. Compared with the prior art, the trivalent chromium electroplate liquid has the beneficial effects that the performance is stable, the service life is long, the coating quality is good, the preparing method is simple, the operation is easy, and the great application prospect and the good use value are achieved.

Trivalent chromium electroplate liquid and preparing method thereof

The invention relates to a method for plating hard chromium in trivalent chromium bath for forming a thick plated layer. The present problem that the thick plated layer cannot be formed on the surface of a workpiece by taking a sexivalent chromium salt as electroplating solution is solved. The technological conditions for electroplating chromium are as follows: adding a defined amount of BSG12 type trivalent chromium electroplating solution into a plating tank according to the size of the workpiece, wherein the electroplating solution meets the demands on: temperature at 15-35 DEG C, current density of 15-45 A/dm2 and PH value of 1.5-2.2; adjusting by using dilute sulphuric acid or sodium carbonate; taking a DSA anode as anode; keeping a distance between cathode and anode within a range of 35mm to 45mm; while electroplating, keeping volume current density less than or equal to 9.8A/L; when electroplating work load reaches 30AH/L, supplementing 50ml/L BSG12 type trivalent chromium electroplating solution; repeatedly filtering tank solution at regular intervals; when potassium sulfate in the solution exceeds 200g/L, reducing the temperature of solution to below 2 DEG C; and after filtering the dissolved potassium sulfate, adjusting the PH value of the solution to be 1.5-2.2 by using the dilute sulphuric acid or sodium carbonate, and keeping working. According to the method provided by the invention, a thick chromium-plated layer which is continuous, compact, complete and excellently jointed with substrate metal is obtained on the steel workpiece; the thickness of the chromium-plated layer can reach 40 microns; and the microhardness HV is more than or equal to 850.

Method for plating hard chromium in trivalent chromium bath for forming thick plated layer

The present invention discloses an additive of an electrolyte for trivalent chromium electroplating of a thick chromium plating layer, and an electrolyte preparation method thereof. The additive is an aqueous solution prepared by using deionized water, and comprises at least a light metal compound and at least an organic carboxylic acid or carboxylate, wherein the concentration of the light metal compound is 80-900 g/L or 60-600 g/L, and the concentration of the organic carboxylic acid or carboxylate is 30-500 g/L. The preparation method comprises: adding a light metal compound and an organic carboxylic acid or carboxylate to deionized water under stirring, aging for 5-10 h at a temperature of 80 DEG C to prepare the additive, adding half of deionized water to a plating tank according to an electrolyte preparation volume, adding chromium sulfate or chromium chloride, formic acid or a formate, boric acid, a conducting salt potassium sulfate or potassium chloride and the additive according to a certain concentration, adding deionized water to achieve the electrolyte preparation volume, and aging for 24 h at a temperature of 40 DEG C to prepare the electrolyte, wherein the pH value of the electrolyte is adjusted to 1-3 so as to perform electroplating. With the electrolyte prepared by using the additive, the trivalent chromium electroplating time can be effectively prolonged, and the chromium plating layer thickness can be increased.

Additive of electrolyte for trivalent chromium electroplating of thick chromium plating layer, and electrolyte preparation method

The invention relates to a processing method of a spinning roller. The method comprises the following steps: 1, preparing a chromium electroplating solution composition; 2, taking a seamless steel pipe, sealing the inside of the seamless steel pipe, exposing the peripheral surface of the seamless steel pipe, controlling the current density in a range of 16-20A/dm under stirring at 29-35DEG C, adjusting the pH value of the chromium electroplating solution to 2.5-3.1, and electroplating an anode electrode highly pure graphite electrode for 40-80min to form a hard chromium layer on the surface of the seamless steel pipe; and 3, carrying out laser drilling on the peripheral surface of the seamless steel pipe to obtain the spinning roller. The spinning roller produced through the method has the advantages of high surface smoothness, good dynamic balance, greatly prolonged service and uncontemplated technical effects.

Processing method of spinning roller

The invention provides a trivalent chromium electroplating solution of a sulfate system The trivalent chromium electroplating solution is characterized by comprising the following components in molarconcentration (mol/L): chromium sulfate02-06, potassium sulfate 05-15, ammonium bromide 002-05, boric acid 05-12, sodium hypophosphite 01-1, ferrous sulfate 001-01, complexing agent 02-20, thickening agent 001-05 and the balance of water The invention also discloses an electroplating method for the electroplating solution Compared with the prior art, the electroplating solution and the electroplating method have the advantages that: the electroplating solution is clean and pollution free, the thickness of the plating layer reaches 20 to 80mu m, the plating layer is smooth with few cracks and high bonding force, the source of raw materials is rich, the cost is lower, the performance-to-price ratio is good, the electroplating solution can be continuously used for electroplating for 05 to 5 hours, the hardness of the plating layer is 600 to 700HV, and after thermal treatment, the hardness of the plating layer can reach 1,200HV

Jiamin Shao

Papers

Trivalent chromium electroplating solution of sulfate system and electroplating method thereof