The current market for sintered tungsten carbide is currently about $2.6 billion dollars annually. It is estimated that approximately $450 million annually could be converted to the new microwave sintered tungsten carbide material with significant performance improvements over a broad range of applications.
High-temperature processing (>800°C, or 1470°F) of materials such as cemented carbides, powder metals, composites and ceramics can be carried out routinely with a new and innovative continuous sintering process that uses microwave energy. The continuous process has been developed commercially to sinter cemented tungsten carbide (WC). The key to uniformity and property improvement is the quick movement of the parts into, through and out of the microwave energy zone to ensure rapid heating, sintering and quenching of the parts to impart the desired properties.
Processing differences over conventional sintering techniques usually are beneficial and contribute to improved mechanical properties of the final product. Since the energy is directly transferred internally to the part, the process is orders of magnitude shorter than conventional processing and much more energy efficient.
Continuous microwave sintering of cermets, ceramics and metals is barely explored to date. However, the implications of the properties obtained using microwave sintering of tungsten carbide are both far-reaching and exciting. Some products such as tungsten-carbide substrates for polycrystalline diamond compact (PDC) have been fully commercialized, while feasibility for cutting tools, machining inserts, bearings and a wide variety of wear parts has been demonstrated. The potential for a new family of tungsten carbide and diamond and tungsten carbide and cubic boron nitride (CBN) concretions is also significant both for cutting and wear applications.
Principal developmental applications at the current time include cutting inserts for use in oilfield and mining drill bits and tools, a variety of nozzle applications, wire drawing dies, seals and wear rings, and cutting tools. Initial field-testing is underway in several of these applications. In addition, efforts are underway to further develop the technology into an integrated manufacturing process, and to scale up the microwave reactors to accommodate larger parts. Continuous microwave sintering furnaces have been designed and manufactured in three sizes, and are commercially available. The furnaces are adaptable for microwave sintering a variety of commercial products, and compared with sinter-hip furnaces, they are both more cost effective and more energy efficient.
Microwave sintering provides significant improvements in the properties of tungsten carbide, specifically improvements in erosion resistance, abrasion resistance, corrosion resistance, hardness, toughness and density. Further, the technology enables the manufacture of materials such as extremely fine grain (nanophase) carbide without grain growth inhibitors and the manufacture of diamond carbide or CBN-carbide composites not feasible using any other current commercial technology. The property improvements are primarily due to the short sintering times (5 minutes or less) compared with conventional sinter-hip processes (10 hours or more).
Dennis Tool has developed commercial microwave sintering furnaces since 1996, as well as several tungsten carbide products with enhanced properties due to the microwave sintering process. This worked stemmed from an agreement with the Penn State Research Foundation to further develop and commercialize this technology.