Exploring the Durability of Silicon Carbide in Harsh Environments

Silicon carbide is a strong compound formed through the high-temperature chemical reaction between silicon and carbon, with an extremely durable crystalline structure making it suitable for use in harsh environments.

Silicon carbide requires stringent quality controls during its production process to ensure its longevity in harsh working environments. We will explore what factors impact its longevivity.

Corrosion Resistance

SiC is an extremely hard, dense material composed of different forms or polytypes of silicon carbide crystal structure with carbon atoms arranged tetrahedrally to make up its layers or polytypes, producing structures with carbon atoms arranged tetrahedral bonds between carbon atoms arranged as layers or polytypes that create its unique corrosion resistant qualities. Pressureless sintered silicon carbide (C/C-SiC) resists all acids (hydrochloric and sulfuric), bases solvents and oxidizing environments like nitric acid while remaining corrosion resistant enough that solid crucibles made of C/C-SiC are frequently employed as furnace lining applications.

Corrosion of SiC materials can be extremely complex, depending on multiple factors. Corrosion resistance of materials depends on their thickness and depth of oxide layer that develops during oxidation processes; additionally, chemical and physical mechanisms responsible for producing the famed parabolic oxidation rate remain incompletely understood.

Long-term corrosion tests are necessary to evaluate the effect of corrosive environments on material strength. Long-term corrosion can increase surface flaws that decrease strength and durability of materials over time.

Elkem conducted extensive corrosion sensitivity analyses of four types of SiC to SiC plate joints joined using metal diffusion bonding with either molybdenum or titanium interlayer, reaction sintering, and the sintering of SiC nanopowder. All samples endured five-week hydrothermal tests at elevated temperature without radiation contamination during five-week hydrothermal testing at elevated temperature.

Thermal Expansion Resistance

Silicon Carbide (SiC) is an extremely hard synthetic material, lying somewhere on the Mohs scale between Alumina (9), at 9 on average, and Diamond (10 on average). SiC finds use as abrasives and wear-resistant parts in mechanical applications; for refractory linings of industrial furnaces and ceramics; as refractory coatings on aircraft fuel tank linings; as refractory linings in furnaces used by industry; and semiconductor electronic devices operating at high temperatures.

Silicon carbide is a remarkable thermomechanical ceramic material with a low thermal expansion coefficient, which enables it to maintain its shape and size during rapid temperature fluctuations and make products that operate in extreme environments more reliable.

Silicon carbide possesses exceptional mechanical properties and boasts great thermal conductivity with a broad operating temperature range, as well as being highly resistant to corrosion and chemical attack, making it suitable for harsh environment applications in industries like automotive, aerospace and electronics.

This book presents microsystem technology based on both bulk and thin film silicon carbide (SiC), covering its rise to prominence as an essential platform for harsh environment microsystems by combining electronic device fabrication with mechanical MEMS devices. This book also investigates the difficulties inherent in combining various processes and materials into usable sensor modules; particularly temperature mismatch between components as well as SiC’s environmental sensitivities are explored extensively, while discussing state of the art in both bulk material SiC technology as well as SiC thin film technologies is covered extensively.

Wear Resistance

Tungsten Carbide (WC) is an important and versatile alloy used in multiple applications, featuring extreme hardness, high conductivity, low thermal expansion and resistance to corrosion. Tungsten carbide is created when pure tungsten powder is mixed with other metals such as carbon, nickel or cobalt using a process called sintering; once formed into shapes for specific uses by pressing and forging, most commonly cutting tools. Tungsten’s extreme durability extends much further than other metals used for cutting tools; additionally it is often utilized by military units using an attack tactic called kinetic bombardment, where bullets fired directly against enemies to penetrate armor protection and penetrate enemy defenses.

Tungsten carbide (WC) is widely utilized for precision engineering due to its ability to withstand very high speeds and pressures, boasting the highest Young’s modulus, hardest surface, lowest thermal expansion rate and best wear resistance of all metals. Furthermore, WC’s very ductility allows it to be formed into rods or extruded as wire such as in incandescent light bulbs.

Tungsten carbide is notoriously fragile and susceptible to cracking or breaking under heavy impacts, making it more prone to impacts than precious metals like gold and platinum. Yet it remains popularly used in military applications where shock resistance is vital, such as at the NCSU crater test facility using buffer disks made of tungsten carbide to absorb projectile impacts.

Electrical Conductivity

Silicon carbide’s unique combination of ceramic and semiconductor properties make it a highly adaptable material, suitable for industrial and electronic uses. Due to these properties, silicon carbide electronics can operate even in harsh environments with high temperatures and voltage levels that would usually disqualify other electronics from performing properly.

Chemically speaking, silicon carbide is an incredibly stable material. It resists most acids (hydrochloric, sulphuric and hydrofluoric), salts and alkalis with the exception of concentrated sulfuric acid; furthermore it does not react with water; making it an ideal material choice for components requiring prolonged liquid exposure.

Silicon carbide offers excellent electrical properties due to its atomic structure. It crystallizes into close-packed structures containing covalently-bonded layers of carbon and silicon. These layers may be arranged into different configurations called polytypes; each polytype being distinguished by its own stacking sequence, giving rise to various crystal structures each with unique properties.

Silicon carbide’s multiple properties place it at the forefront of technological innovation. Utilization in extreme and high-performance engineering applications such as pump bearings, valves, sandblasting injectors and extrusion dies as well as fabrication of semiconductor devices that operate under extreme environments can lead to significant improvements across industries.