What is the role of sodium acetate in electroless Ni plating?
This means that increasing the concentration of sodium acetate promotes the oxidation of hypophosphite and therefore the reduction of nickel. These results are in agreement with the results of the deposition rate calculated by the gravimetric method.
What chemicals are used in electroless nickel plating?
Electroless nickel plating is a chemical process which reduces nickel ions in solution to nickel metal by chemical reduction. The most common reducing agent used is sodium hypophosphite. Alternatives are sodium borohydride and dimethylamine borane but they are used much less frequently.
Is sodium hypophosphite a reducing agent?
Sodium hypophosphite is used as a reducing agent. The following is the mechanism of reduction. Oxidation of hypophosphite to orthophosphate in the presence of a catalyst. [H2 is absorbed on the catalyst surface and (H2PO2)− is transformed to (HPO3)=.]
How do you make sodium hypophosphite?
1. A process for preparing sodium hypophosphite, comprising treating an aqueous mixture of calcium hydroxide and sodium carbonate with free phosphorus, the reaction mixture being heated at a temperature between about 70 and 100 C. for a plurality of hours to form an aqueous solution of sodium hypophosphite.
What is the reducing agent in electroless plating of nickel?
Widely used reducing agents are sodium hypophosphite, sodium borohydride and dimethylamine borane. Complexing agents keep the nickel in a stable complex until it’s needed for plating. The choice of complexors determines the deposit alloy and thus its properties.
What materials can be electroless plated?
Electroless deposition or plating of metals such as silver, aluminum, copper, nickel, and iron is a uniform coating of metallic layer on the surface of fibers through chemical reduction of metal ions in an aqueous solution and the subsequent deposition of metal without the use of electrical energy.
What is lead Hypophosphite?
Lead hypophosphite can be made by precipitation induced by the reaction of an unsaturated solution of calcium hypophosphite with an unsaturated solution of lead nitrate. In actual practice the calcium hypophosphite solution has a concentration of between 4 and 15%, preferably about 11%.
How is electroless nickel plating done?
The process involves dipping the substrate in a water solution containing nickel salt and a phosphorus-containing reducing agent, usually a hypophosphite salt. It is the most common version of electroless nickel plating (EN plating) and is often referred by that name.
How do you make hypophosphorous acid from sodium hypophosphite?
Hypophosphorous acid can also be made by passing sodium hypophosphite through a cation exchange column, where sodium is exchanged for hydrogen. This process requires a very large cation exchange column, and also generates an aqueous waste stream that contains phosphorus, which is difficult to dispose of.
How do you make calcium Hypophosphite?
Calcium hypophosphite can be prepared by neutralization process or synthetic method of lime and yellow phosphorus . Neutralization process means that neutralization of hypophosphite and slaked lime get calcium hypophosphite.
What is the hardness of electroless nickel plating?
With an as-plated hardness from 58 to 62 Rc, low phosphorus electroless nickel provides excellent wear resistance, good corrosion resistance in alkaline conditions and has a high melting point.
How do you make electroless nickel plating solution?
1. An electroless nickel plating solution comprising a water-soluble nickel salt in an amount of 0.01. to 1 mol/liter, a reducing agent in an amount of 0.01 to 1 mol/liter, a complexing agent in an amount of 0.01 to 2 mol/liter, and a polythionate or dithionite in an amount of 0.01 to 100 mg/liter.