A new method of deposition of Nickel alloy coatings

A new method of deposition of Nickel alloy coatings

Subject :Science and Technology

Concept:

• A new method of deposition of Nickel alloy coatings on high-performance materials in engineering applications can replace environmentally toxic chrome coatings.
• The coatings obtained are also highly corrosion-resistant and useful for the plastic ware industry.
• With ever-increasing demand for high-performance materials in engineering applications, nano-crystalline coatings can cater to the need for the replacement of environmental hazardous chrome coatings.
• Chrome coatings have been used in plastic bottling industry to improve the service life of die-casting components. However, chrome plating is a toxic process, and the stringent standard permissible exposure limit (PEL) for toxic hexavalent chromium and all its compounds has to be complied in all chrome plating industrial workplaces. Finding a procedure for adhering to this limit is a challenge for scientists.
• The pulsed current effect was used for nano-crystalline coatings wherein high instantaneous current density for very small duration resulted in high rate of nucleation.
• Unlike in conventional direct current plating, the coatings were virtually porosity free, crack free with minimal hydrogen uptake. The use of pulsed current resulted in the nano-crystallization of nickel tungsten alloy coatings with high hardness (700-1200 HV) and wear resistance. The coatings were extremely corrosion resistance and could withstand up to 700 hrs of salt spray.
• The coatings developed at ARCI can withstand temperatures up to 500°C without thermal softening and can improve the life of die components by at least two times than conventional chrome plating.
• They were successfully applied to die-casting components used in plastic bottling industry, wherein the temperatures at the die interface can be over 280°C. With numerous applications in automotive, defense, and aerospace for these coatings, the process know-how is ready for transfer as a replacement for conventional chrome plating.

Impact of Chromium pollution 

• Severely impacting our environment and natural resources, especially water and soil. Excessive exposure could lead to higher levels of accumulation in human and animal tissues, leading to toxic and detrimental health effects like  chromium skin exposure include dermatitis, hypersensitivity reactions, eczema, and kidney or liver damage.
• Several studies have shown that chromium is a toxic element that negatively affects plant metabolic activities, hampering crop growth and yield and reducing vegetable and grain quality, decrease of seed germination, reduction of growth, decrease of yield, inhibition of enzyme, It can alter genetic materials and cause cancer.