BACKGROUND
Protecting mechanical components in harsh environments, such as extreme sliding or rolling contacts, is critical for ensuring the reliability and efficiency of high-demand systems. To protect these components, nanocomposites consisting of hard refractory carbides are employed as wear-resistant coatings. In particular, tungsten carbide-cobalt (WC-Co) based nanocomposites are extensively used due to their excellent hardness, strength, corrosion resistance, and resistance against sliding and abrasive wear. However, methods of application such as Thermal Sprays can require up to 1,000°C, which could lead to undesirable microstructural transformations in both the coatings and the underlying metallic substrates. A method to apply these nanocomposite coatings at low temperatures could help alleviate the reduction in hardness and wear-resistance seen at high temperatures.
SUMMARY OF TECHNOLOGY
Researchers at Oklahoma State University have developed a method to fabricate nanocomposite coatings at low temperatures (100°C) through stress-activated sintering of metal/ceramic nanoparticles on metallic components. This method involves introducing nanoparticle-containing fluids to pressurized sliding/rolling interfaces, where elevated contact stresses drive nanoparticle sintering. WC-Co nanoparticles are suspended in a carrier fluid, which was passed through the pressurized contact of ball and disc specimens in rolling and sliding conditions using a ball-on-disc tribometer. Using pressure-assisted sintering, the nanocomposite coatings are formed with an average thickness of 16 nanometers. Optical interferometry measurements of growth kinetics revealed this deposition process is ultrafast, achieving a uniform and steady-state coating thickness within ten minutes of contact cycles. By conducting scanning electron microscopy and electron dispersive X-ray spectroscopy of coated surfaces, it was confirmed that these coatings consist of WC and Co phases. It is also shown in this application that the application of an electric field can further accelerate the sintering process. This method developed by OSU researchers significantly reduces the processing temperature, cost, and time compared to many state-of-the-art thermal spray and physical vapor deposition technologies.
POTENTIAL AREAS OF APPLICATION
MAIN ADVANTAGES
STAGE OF DEVELOPMENT
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