What is Plating ?
Plating is a surface covering in which a metal is deposited on a conductive surface.
Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish
การชุบคือ กระบวนการทางไฟฟ้าเคมี ที่นำโลหะจากที่หนึ่งมาเคลือบผิวอีกที่หนึ่ง โดยนำงานมาจุ่มในสารละลายและต่อขั้วไฟฟ้า
การชุบโลหะ เป็นเทคโนโลยีที่มีการใช้งานในภาคอุตสาหกรรมมาอย่างยาวนาน มากกว่า 100 ปี ชุบชิ้นงานเพื่อเพิ่มประสิทธิภาพผิวในหลายด้าน อันได้แก่ เพิ่มการป้องกันสนิม เพิ่มความแข็งแรง เพิ่มความสวยงาม เพิ่มหรือลดความนำไฟฟ้า เพิ่มการป้องกันการกัดกร่อน
Gold plating is a method of depositing a thin layer of gold on the surface of glass or metal, most often copper or silver.
Gold plating is often used in electronics, to provide a corrosion-resistant electrically conductive layer on copper, typically in electrical connectors and printed circuit boards. With direct gold-on-copper plating, the copper atoms have the tendency to diffuse through the gold layer, causing tarnishing of its surface and formation of an oxide/sulfide layer. Therefore, a layer of a suitable barrier metal, usually nickel, has to be deposited on the copper substrate, forming a copper-nickel-gold sandwich.
Metals and glass may also be coated with gold for ornamental purposes, using a number of different processes usually referred to as gilding.
Sapphires, plastics, and carbon fiber are some other materials that are able to be plated using advance plating techniques. The substrates that can be used are almost limitless.
Silver plating has been used since the 18th century to provide cheaper versions of household items that would otherwise be made of solid silver, including cutlery, vessels of various kinds, and candlesticks. In the UK the assay offices, and silver dealers and collectors, use the term “silver plate” for items made from solid silver, derived long before silver plating was invented from the Spanish word for silver “plata”, seizures of silver from Spanish ships carrying silver from America being a large source of silver at the time. This can cause confusion when talking about silver items; plate or plated. In the UK it is illegal to describe silver-plated items as “silver”. It is not illegal to describe silver-plated items as “silver plate”, although this is ungrammatical.
The earliest form of silver plating was Sheffield Plate, where thin sheets of silver are fused to a layer or core of base metal, but in the 19th century new methods of production (including electroplating) were introduced. Britannia metal is an alloy of tin, antimony and copper developed as a base metal for plating with silver.
Chrome plating is a finishing treatment using the electrolytic deposition of chromium. The most common form of chrome plating is the thin, decorative bright chrome, which is typically a 10-μm layer over an underlying nickel plate. When plating on iron or steel, an underlying plating of copper allows the nickel to adhere. The pores (tiny holes) in the nickel and chromium layers work to alleviate stress caused by thermal expansion mismatch but also hurt the corrosion resistance of the coating. Corrosion resistance relies on what is called the passivation layer, which is determined by the chemical composition and processing, and is damaged by cracks and pores. In a special case, micropores can help distribute the electrochemical potential that accelerates galvanic corrosion between the layers of nickel and chromium. Depending on the application, coatings of different thicknesses will require different balances of the aforementioned properties. Thin, bright chrome imparts a mirror-like finish to items such as metal furniture frames and automotive trim. Thicker deposits, up to 1000 μm, are called hard chrome and are used in industrial equipment to reduce friction and wear.
Zinc coatings prevent oxidation of the protected metal by forming a barrier and by acting as a sacrificial anode if this barrier is damaged. Zinc oxide is a fine white dust that (in contrast to iron oxide) does not cause a breakdown of the substrate’s surface integrity as it is formed. Indeed, the zinc oxide, if undisturbed, can act as a barrier to further oxidation, in a way similar to the protection afforded to aluminum and stainless steels by their oxide layers. The majority of hardware parts are zinc-plated, rather than cadmium-plated.