ADVANCED MATERIALS & PROCESSES | JANUARY/FEBRUARY 2024 21 Manufacturers increasingly use exotic materials because of their unique properties, including lightweight, extreme hardness, and the ability to withstand extreme temperatures and highly corrosive environments. Innovation in cutting- edge sectors such as defense, aerospace, biomedical, medical, and energy is driving the coatings industry to meet rising demand for this higher component performance. These coatings are often applied by chemical vapor deposition (CVD) systems that deposit exotic materials in gaseous form as thin film layers on substrates such as metal or glass. Although CVD systems are already widely used for silicon carbide, graphite, and pyrocarbons, industry demand is increasingly embracing even more exotic and, in many cases, rarely (or even never before) deposited coatings including iridium, tungsten, tantalum, hafnium carbide, zinc sulfide, boron phosphide, and titanium diboride. Often, however, incorporating new exotic materials requires much more than modifying an existing CVD system. Instead, experienced system designers are tasked to provide custom systems that resolve challenges based on a unique substrate with varying sizes, uniformity, throughput, and increasingly exotic materials. Challenges can arise when working with exotic precursor materials in a CVD system, starting with the ability to handle each unique material. The process requires converting solid and liquid materials to the gas form needed for film deposition. Venting vapors and off-gases must satisfy stringent explosive atmospheres (ATEX) environmental safety standards, while extremely dirty vacuum conditions within the reaction chamber must also be managed. Usually, a zinc sulfide or titanium diboride coating is going to be outside the scope of most companies. Typically, CVD system designers will piece together a system from different providers of subsystem components such as reactors, pumps, off-gassing, and scrubbers. These systems are not designed from a “global” perspective for the deposition of specific exotic materials. Instead, a better alternative is to create a highly integrated CVD solution designed and built to meet the specific requirements of the exotic material. Whether the precursor is in gas, liquid, or solid form, the material does not need to be a limiting factor. When the component parts of the technology are mastered, working with a new exotic material is relatively easy and can be performed safely. TECHNICAL SPOTLIGHT ACCELERATING EXOTIC MATERIALS USE WITH CUSTOM COATING SYSTEMS Custom equipment designed for the deposition of exotic materials allows advanced coating solutions and ceramic matrix composites to be utilized for applications in automotive, aerospace, defense, energy, and the farthest reaches of space. Chemical vapor deposition systems require precise control of gas flow, temperature, and pressure to achieve desired results.
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