Why is White Fused Alumina 360# Used for Multifunctional Ceramics?
First, What is White Fused Alumina 360#?
White Fused Alumina (WFA): This is a synthetic abrasive produced in an electric arc furnace from high-purity alumina (Al₂O₃). The “white” designation indicates its high purity (typically >99% Al₂O₃), which gives it excellent mechanical properties and chemical inertness. It’s very hard (9 on the Mohs scale, just below diamond) and has high strength. 360# (Grit Size): The “#” refers to the grit size according to the FEPA (Federation of European Producers of Abrasives) standard. 360# is a fine powder with a median particle size of about 22.8 microns. For context, it’s finer than 280# and coarser than 400#. This places it in the category of a fine-grained abrasive filler.
Why is it Ideal for Multifunctional Ceramics?
1. Optimal Balance of Strength and Sintering
Particle Packing: In ceramic processing, a well-packed powder bed sinters (fuses together at high temperature) more densely and uniformly. Using a single, controlled particle size like 360# allows for efficient packing with other ceramic powders in the formulation. Reinforcement: The 360# particles are fine enough to be distributed homogenously throughout the ceramic matrix, acting as a reinforcement phase. They hinder the growth of cracks, significantly increasing the ceramic’s fracture toughness and mechanical strength. Sintering Control: If the alumina particles were much coarser, they wouldn’t integrate well and could create weak points. If they were much finer (e.g., 800# or 1000#), their high surface area could cause excessive and unpredictable sintering shrinkage, leading to warping or defects. 360# offers a “Goldilocks” zone—fine enough to reinforce effectively but not so fine that it disrupts the sintering process.
2. Enhanced Mechanical Properties
High Hardness & Wear Resistance: WFA is one of the hardest materials available. Incorporating it dramatically increases the ceramic’s resistance to abrasion, scratching, and erosion. This is crucial for components like industrial liners, cutting tools, wear plates, and pump seals. High Strength & Rigidity: The strong ionic bonds in the alumina crystal structure translate into high compressive strength and stiffness for the final ceramic product.
3. Excellent Thermal Properties
High Thermal Stability: WFA has an extremely high melting point (~2050°C) and does not decompose. This allows the ceramic composite to maintain its structural integrity and properties at elevated temperatures. Good Thermal Conductivity: Alumina is a decent conductor of heat. This helps in dissipating heat quickly, preventing thermal stress buildup and cracking, which is vital for applications like electronic substrates or heat sinks.
4. Superior Electrical Insulation
Electronic substrates and packages. Insulating components in high-temperature furnaces. Parts requiring electrical isolation along with heat dissipation.
5. Chemical Inertness
Summary: Key Advantages of WFA 360# in a Table
Typical Applications in Multifunctional Ceramics:
Advanced Refractories: For linings in high-wear, high-temperature industrial furnaces. Structural Ceramics: For components in the automotive and aerospace industries (e.g., bearings, valves). Electronic Ceramics: Used as a filler in substrates or insulating components. Wear-Resistant Parts: Tiles, liners, nozzles, and grinding media subjected to severe abrasion.