Applications of Metal
Powders in Construction
Metal powders are used as bonding agents in the fabrication of diamond cutting and grinding tools. Diamond grains are sintered into the functional article, such as a saw blade or drill bit. Diamond, being the hardest material known, provides superior grinding and cutting efficiency in conjunction with extremely high wear resistance. Copper, tin and bronze powders are employed as bonding agents to impart high wear resistance and heat dissipation in order to maximise the lifespan of the tool.
Welding & Brazing
These are similar processes where metal parts are directly fused together. In welding, higher temperatures are required to melt the constituent metal materials, while brazing requires lower temperatures by utilising metal powders as bonding agents. The bonding agent used must have good wetting properties with respect to the metal substrate. This will ensure that when the bonding agent is heated and becomes liquefied it will efficiently penetrate into the pores and cavities throughout the substrate surface, ensuring strong bonding is achieved. Copper powders provide good mechanical properties in this application and are well suited for nickel substrates. The addition of tin powder lowers the melting point of the bonding flux and can improve wetting for a number of other substrates, such as stainless steel.
Sintered Components (Iron admix, infiltration)
Sintering can be viewed as a similar process to brazing, except that it occurs at the microscopic level between individual metal particles. Generally speaking, a fine metal powder is compacted into a mold and then heated, often under pressure, in order to fuse the individual particles into an interconnected network. The inherent porous structure of the resulting material provides increased tolerance to heat stress and deformation. This technique is advantageous since it allows for much lower processing temperatures than in traditional metallurgy where substances like steel are cast in a molten state. Sintering enables the fabrication of intricate metal components with a higher level of precision than can typically be accommodated with traditional metal casting. Iron, copper, aluminum, and their various alloys are common ingredients used in the production of sintered steel components. As in the case of brazing, relatively low melting temperatures and good wetting characteristics make copper and tin-based powders particularly well suited as sintering materials.
These are sintered nonmetals broadly classified under two subcategories, metal oxides and non-oxides. Whereas metals and metal alloys are good conductors of heat and electricity to varying degrees, ceramics are generally employed for their ability to function as insulators of both heat and electricity. Copper and bronze powders are sometimes used to deposit metallic coatings onto ceramic substrates in order to achieve an aesthetic effect with its lustrous finish, while maintaining the insulating properties of the base ceramic. Copper-ceramic composites are often employed in the fabrication of capacitors.
Coloured Panels and Flooring
Metal powders find utility in building materials not only for their functionality, but also for their aesthetic effect. Copper, bronze, and tin powders are formulated into epoxy and other clear coatings to achieve a reflective metallic finish on concrete flooring and other masonry. An array of distinctive metallic tones can be achieved with copper and its alloys. These also have an added advantage of being especially resistant to corrosion.