Out of this World
An optics experiment on board the International Space Station needed an electrically conductive,
non-reflective surface. By Dean Jobb
Nickel magazine, March, 2004 --The specs for the International Space Station include
a work surface for scientists conducting optical experiments. Although the designers of the optics bench knew
what they needed, a material that would meet all of their challenges seemed - literally - to be out of this
world.
"They wanted to make sure that no stray light was going to shine into their instruments," recalls Michael Feldstein, president of Trenton, N.J.-based Surface Technology, Inc. "They also wanted to make sure, as they slide the different pieces of equipment around in grooves and then clamp them down in different locations, that they weren't going to wear into the coating. And the last thing is, it had to be electrically conductive so that they can ground it, so that there wouldn't be any stray charge that could harm their equipment."
NASA's engineers were surprised to discover that a stock coating could meet their demanding specifications. "They thought they were going to have to reinvent the wheel somehow," Feldstein notes.
The solution turned out to be an aluminum bench clad in an electroless nickel coating that Surface Technology has been producing for two decades. NiPlate 700 incorporates ultra-fine silicon carbide particles that create an exceptionally hard, wear-resistant surface that conducts electricity, and, as it turns out, its matte-grey finish absorbs light.
NiPlate 700 is part of a family of nickel-based coatings that Surface Technology has developed since it was founded in 1973. The company is the world's leading producer of composite electroless nickel coatings, holding more than 90 patents on its processes for bonding nickel and particles of diamond, silicon carbide, aluminum oxide and other materials into durable, high-performance finishes.
Electroless nickel is manufactured through a chemical process and, as the name suggests, without resorting to electrolysis to coat surfaces. Nickel sulphate is added to bath of reducing agents, buffers and stabilizers to create a controlled chemical reaction that deposits the nickel on the target surface.
The process offers an alternative to chromium-nickel plating, as manufacturers and regulators strive to reduce the use of chromium. Long-term exposure to the metal poses serious health and environmental risks.
Electroless nickel requires less energy to produce and creates a uniform finish, even on intricate surfaces, so there's no need to grind down high spots. The low energy requirements save time and money, and reduce the release of metal into the environment.
Surface Technology's process also greatly reduces the amount of nickel used. Particles typically account for 25 to 30 per cent of its composite coatings, can be applied in a thinner layer and will last longer than nickel plating alone. "It will certainly last twice as long as conventional electroless nickel, so therefore you've eliminated half of the nickel already," says Feldstein. And when it does wear through, the residual coating can be chemically dissolved to reclaim the nickel and a new one can be applied in its place - an environmentally responsible and low-cost method of rejuvenating parts.
The primary market for NiPlate 700 is the textile industry. Spinning machines operate at speeds of up to 150,000 revolutions per minute and their intricate components must hold up to constant contact with abrasive fibres. Manmade fibres can be extremely coarse and raw cotton contains sand, dirt and other debris from the fields that can wear down metal surfaces.
"They're in contact with these fibres, they're running 24 hours a day, seven days a week, constantly for years," Feldstein notes. NiPlate makes components last longer, reducing maintenance and downtime and helping textile manufacturers to compete.
The petroleum industry relies on NiPlate 700 to make pumps and drills last longer. In manufacturing, it provides a durable surface that will extend the life of moulds used to cast everything from plastics to door panels for cars. Another composite coating, marketed under the brand name NiSlip, incorporates particles of Teflon to create a corrosion-resistant, non-stick surface for food-handling equipment and to ensure castings do not stick to moulds.
Surface Technology has also developed a coating it calls Illumi-layer that combines nickel with phosphorescent particles that glow under ultraviolet light. While Feldstein admits it may seem "a little esoteric" at first, there are practical applications.
Manufacturers could line moulds with Illumi-layer before applying a top coat of NiPlate 700; regular inspections with an ultraviolet light would reveal when the outer layer has worn through, enabling the mould to be recoated and returned to service before the base metal is damaged. The tell-tale coating could also be applied to car and aircraft components to make it easy to detect lower-quality counterfeit parts. "If an installer just shines a light on it before they put it on, and it glows back that colour, you know that it's an official authentic part," Feldstein says.
Surface Technology is exploring new applications that promise to move its coatings from the factory floor to play a bigger role in finished products. Car makers, aircraft manufacturers and the military are working to reduce the use of chrome and the company is testing an array of potential applications.
"The key word is really synergy," Feldstein says, "synergy between the properties of the particles and the properties of the nickel - the wear resistence and hardness and corrosion-resistence of the nickel, and add to that whatever properties you really want to incorporate."
Dean Jobb is a Halifax, Nova Scotia-based freelance writer.
PHOTOS: NASA (top) and Surface Technology, Inc.
Michael Feldstein |
