Applications of Metal Powers
in Process Plants & Equipment
A number of chemical and industrial processes involve filtration of materials from fluid streams that make the use of common cellulose or glass fiber-based filters prohibitive due to their inability to withstand the chemical or physical environment, such as corrosive mixtures or high pressure systems. Metal filter membranes derived from sintered copper powders are especially well suited for these applications. Metallic filtration membrane porosity can be tailored through modulation of the constituent metal powders’ particle size and sintering conditions. Copper filtration membranes are additionally functional in water purification due to their natural tendency to exhibit antimicrobial properties.
Bronze-Filled PTFE Seals
X-ray spectroscopy and imaging techniques are valuable tools utilised throughout science and medicine. While x-ray radiation provides a means to gather otherwise indiscernible information, such as medical x-ray images that enable doctors to identify the precise location of damaged bone tissue, prolonged or elevated exposure to this form of radiation can produce detrimental health effects. Historically lead-based materials have been used to shield those in work environments where x-ray generating equipment is utilised. Lead possesses both a high atomic number and density, as well as being inexpensive and malleable. These qualities made it an ideal material for x-ray shielding, except that lead itself is now known for its own associated health hazards. Copper and tin metal are suitable replacements for lead in x-ray shielding applications due to their cost and ease of processing. Their reduced atomic number and density, which contribute to x-ray shielding efficiency, is offset by fabrication of incrementally larger shield thicknesses.
Surface Engineering (e.g. Cold and Thermal Spray)
For many applications of metals, often only a thin layer of the material is required to accomplish its intended purpose. Thermal spray, and more recently cold spray, techniques are a clean and efficient means of applying metallic surface coatings. Because of the diverse functionalities of copper and its alloys in conjunction with the ease in which these metal powders can be thermalised and dispersed into aerosol form, spray-applied copper-based coatings provide a solution to a number of challenges across a broad range of industries. Some more common applications include RFI and EMI shielding, corrosion resistant and anti-fouling coatings.
Friction (brakes and clutches)
Conductive Paste, Plastics, and Paint
Copper powder is utilised in a variety of composite formulations to impart electrical or thermal conductivity on otherwise insulating paint, plastic, and related compositions. Conductive paints of this sort are used to construct the conductive pathways on printed circuit boards (PCBs). When plastic mechanical parts and similar components are in close proximity to heat generating sources, such as motors or points of friction, it may be necessary to improve heat transfer in order to increase the rate at which heat is removed from the system to alleviate the effects of prolonged thermal exposure. Thermal conductivities can be increased through the use of copper-containing composite plastics.
Welding, Soldering, and Brazing
Thermal Management (Heat Pipe)
One of the most common challenges faced in chemical and industrial process design and execution is the efficient removal of heat from a system. Common sources of heat are derived from friction between mechanical parts, exothermic chemical processes, and resistance in electrical components, especially in confined spaces. Heat pipes are sealed heat transfer systems that are essentially just a liquid filled pipe, typically copper tubing with water. Their utility lies in their ability to transfer heat from hot zones to a cooling zone or heat sink such as a water bath or cooling fan via a porous liner within the pipe’s inner surface. The porosity of this layer, known as a wick, is responsible for circulating the cooled or condensed water via capillary action from the cold zone back to the hot zone where it becomes volatilised once again where the cycle repeats continuously until equilibrium is reached between the internal cooling water and the hot zone. The wick is crucial to the function of a heat pipe, owing its utility to its porous structure which facilitates capillary action of the cooling liquid from the cold zone to the hot zone. This porous structure is generally fabricated via a sintering process. Copper powder is ideal for these systems due its excellent thermal conductivity and ease of processing by sintering.