1. Product Principles and Crystal Chemistry
1.1 Composition and Polymorphic Structure
(Silicon Carbide Ceramics)
Silicon carbide (SiC) is a covalent ceramic substance made up of silicon and carbon atoms in a 1:1 stoichiometric proportion, renowned for its remarkable hardness, thermal conductivity, and chemical inertness.
It exists in over 250 polytypes– crystal frameworks varying in piling sequences– among which 3C-SiC (cubic), 4H-SiC, and 6H-SiC (hexagonal) are the most technologically appropriate.
The strong directional covalent bonds (Si– C bond power ~ 318 kJ/mol) result in a high melting point (~ 2700 ° C), reduced thermal growth (~ 4.0 × 10 ⁻⁶/ K), and superb resistance to thermal shock.
Unlike oxide porcelains such as alumina, SiC lacks an indigenous glassy stage, contributing to its security in oxidizing and destructive ambiences as much as 1600 ° C.
Its broad bandgap (2.3– 3.3 eV, depending on polytype) also grants it with semiconductor residential or commercial properties, making it possible for dual use in structural and electronic applications.
1.2 Sintering Obstacles and Densification Approaches
Pure SiC is incredibly tough to compress as a result of its covalent bonding and low self-diffusion coefficients, demanding using sintering aids or sophisticated processing techniques.
Reaction-bonded SiC (RB-SiC) is generated by penetrating permeable carbon preforms with molten silicon, developing SiC in situ; this approach returns near-net-shape components with residual silicon (5– 20%).
Solid-state sintered SiC (SSiC) makes use of boron and carbon additives to promote densification at ~ 2000– 2200 ° C under inert environment, achieving > 99% theoretical thickness and superior mechanical residential or commercial properties.
Liquid-phase sintered SiC (LPS-SiC) employs oxide ingredients such as Al Two O TWO– Y TWO O ₃, creating a transient fluid that enhances diffusion however may lower high-temperature stamina due to grain-boundary phases.
Warm pushing and trigger plasma sintering (SPS) supply rapid, pressure-assisted densification with fine microstructures, suitable for high-performance components requiring minimal grain growth.
2. Mechanical and Thermal Efficiency Characteristics
2.1 Strength, Firmness, and Use Resistance
Silicon carbide ceramics show Vickers hardness values of 25– 30 GPa, second only to ruby and cubic boron nitride amongst design materials.
Their flexural toughness normally varies from 300 to 600 MPa, with fracture durability (K_IC) of 3– 5 MPa · m ¹/ ²– moderate for porcelains however enhanced via microstructural engineering such as hair or fiber reinforcement.
The mix of high hardness and flexible modulus (~ 410 GPa) makes SiC exceptionally immune to rough and abrasive wear, outmatching tungsten carbide and solidified steel in slurry and particle-laden settings.
( Silicon Carbide Ceramics)
In commercial applications such as pump seals, nozzles, and grinding media, SiC components demonstrate service lives several times much longer than conventional alternatives.
Its low thickness (~ 3.1 g/cm FOUR) additional contributes to use resistance by minimizing inertial pressures in high-speed turning parts.
2.2 Thermal Conductivity and Stability
One of SiC’s most distinguishing features is its high thermal conductivity– varying from 80 to 120 W/(m · K )for polycrystalline types, and as much as 490 W/(m · K) for single-crystal 4H-SiC– going beyond most metals other than copper and aluminum.
This residential property allows reliable warmth dissipation in high-power electronic substrates, brake discs, and heat exchanger components.
Combined with reduced thermal growth, SiC exhibits impressive thermal shock resistance, quantified by the R-parameter (σ(1– ν)k/ αE), where high worths indicate resilience to rapid temperature changes.
For example, SiC crucibles can be heated up from area temperature level to 1400 ° C in mins without breaking, an accomplishment unattainable for alumina or zirconia in similar conditions.
Moreover, SiC keeps toughness up to 1400 ° C in inert environments, making it perfect for heating system components, kiln furnishings, and aerospace elements subjected to extreme thermal cycles.
3. Chemical Inertness and Deterioration Resistance
3.1 Actions in Oxidizing and Minimizing Environments
At temperatures below 800 ° C, SiC is extremely secure in both oxidizing and minimizing settings.
Over 800 ° C in air, a protective silica (SiO ₂) layer kinds on the surface area through oxidation (SiC + 3/2 O TWO → SiO ₂ + CARBON MONOXIDE), which passivates the material and slows further deterioration.
However, in water vapor-rich or high-velocity gas streams above 1200 ° C, this silica layer can volatilize as Si(OH)FOUR, causing increased economic downturn– a vital consideration in wind turbine and burning applications.
In reducing environments or inert gases, SiC remains stable as much as its disintegration temperature level (~ 2700 ° C), without phase modifications or toughness loss.
This stability makes it ideal for liquified steel handling, such as aluminum or zinc crucibles, where it withstands moistening and chemical strike far better than graphite or oxides.
3.2 Resistance to Acids, Alkalis, and Molten Salts
Silicon carbide is practically inert to all acids other than hydrofluoric acid (HF) and strong oxidizing acid mixes (e.g., HF– HNO ₃).
It shows outstanding resistance to alkalis approximately 800 ° C, though prolonged direct exposure to molten NaOH or KOH can create surface area etching via formation of soluble silicates.
In molten salt settings– such as those in focused solar energy (CSP) or atomic power plants– SiC shows premium deterioration resistance contrasted to nickel-based superalloys.
This chemical effectiveness underpins its usage in chemical process tools, including shutoffs, linings, and warmth exchanger tubes dealing with aggressive media like chlorine, sulfuric acid, or salt water.
4. Industrial Applications and Emerging Frontiers
4.1 Established Makes Use Of in Power, Protection, and Manufacturing
Silicon carbide porcelains are integral to countless high-value commercial systems.
In the energy industry, they work as wear-resistant liners in coal gasifiers, elements in nuclear fuel cladding (SiC/SiC composites), and substratums for high-temperature solid oxide fuel cells (SOFCs).
Defense applications include ballistic shield plates, where SiC’s high hardness-to-density ratio provides exceptional protection versus high-velocity projectiles contrasted to alumina or boron carbide at lower expense.
In manufacturing, SiC is used for accuracy bearings, semiconductor wafer dealing with parts, and unpleasant blowing up nozzles as a result of its dimensional security and pureness.
Its use in electrical automobile (EV) inverters as a semiconductor substratum is quickly growing, driven by efficiency gains from wide-bandgap electronics.
4.2 Next-Generation Advancements and Sustainability
Continuous study concentrates on SiC fiber-reinforced SiC matrix composites (SiC/SiC), which exhibit pseudo-ductile actions, boosted durability, and maintained stamina above 1200 ° C– perfect for jet engines and hypersonic automobile leading sides.
Additive production of SiC by means of binder jetting or stereolithography is advancing, making it possible for complicated geometries formerly unattainable through traditional forming methods.
From a sustainability viewpoint, SiC’s durability decreases replacement regularity and lifecycle exhausts in industrial systems.
Recycling of SiC scrap from wafer slicing or grinding is being developed through thermal and chemical recuperation processes to reclaim high-purity SiC powder.
As industries push toward higher efficiency, electrification, and extreme-environment procedure, silicon carbide-based ceramics will remain at the forefront of advanced products design, connecting the void in between architectural resilience and functional convenience.
5. Distributor
TRUNNANO is a supplier of Spherical Tungsten Powder with over 12 years of experience in nano-building energy conservation and nanotechnology development. It accepts payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you want to know more about Spherical Tungsten Powder, please feel free to contact us and send an inquiry.
Tags: silicon carbide ceramic,silicon carbide ceramic products, industry ceramic
All articles and pictures are from the Internet. If there are any copyright issues, please contact us in time to delete.
Inquiry us