Natural Abrasives
Natural abrasives include natural corundum, emery, quartz, pumice, diatomaceous earth, and others. The chemical composition of natural corundum is aluminum oxide; primarily mined in South Africa, it is used for polishing and grinding glass. Emery is also a natural form of aluminum oxide; generally speaking, it is less pure than corundum. Primarily sourced from Greece and Turkey, it is widely used in the manufacture of abrasive cloth and sandpaper. Quartz was the earliest material used for grinding wheels and remains in use today for manufacturing cutting tools and processing glass. Pumice is of volcanic origin and serves as a raw material for producing polishing powders. Diatomaceous earth is used as an ingredient in polishing powders and oilstones. Other natural abrasives include talc, silica, feldspar, black silica, and chalk. Garnet sand is a natural abrasive produced by processing raw garnet ore; due to its eco-friendly nature and high hardness, it is widely utilized in waterjet cutting and surface treatment applications, where it can partially replace energy-intensive artificial abrasives.
Common Artificial Abrasives
Artificial abrasive products are primarily categorized into two major groups: corundum abrasives and silicon carbide abrasives. Brown corundum abrasive-whose main component is Al₂O₃-possesses moderate hardness, high toughness, and sharp grains; it is relatively inexpensive and suitable for processing metals with high tensile strength. White corundum abrasive has a hardness slightly higher than that of brown corundum but exhibits lower toughness; during grinding, it cuts easily into the workpiece, features excellent self-sharpening properties, generates minimal heat, and offers strong grinding capability and high efficiency. Single-crystal corundum abrasive consists of grains composed of individual crystals, featuring well-defined polyhedral cutting edges; it possesses high hardness and toughness, strong grinding capability, and generates very little heat during grinding operations. Black silicon carbide, green silicon carbide, cubic silicon carbide, and cerium-doped silicon carbide abrasives all fall under the category of silicon carbide abrasives. Their primary component is silicon carbide (SiC); characterized by high hardness, high brittleness, sharp abrasive grains, good thermal conductivity, and strong wear resistance, they are particularly well-suited for processing hard and brittle metals as well as non-metallic materials.
Superhard Abrasives
Superhard abrasives primarily consist of diamond and cubic boron nitride (CBN). Diamond abrasives are commonly used for grinding hard and brittle materials such as cemented carbides, optical glass, ceramics, and natural stone. CBN abrasives can withstand high temperatures ranging from 1300°C to 1400°C; they exhibit high chemical inertness toward iron-group elements, possess excellent thermal conductivity, and offer high material removal rates, high grinding ratios, and long tool life when grinding steel. Consequently, they are well-suited for grinding high-hardness, high-toughness metals such as hardened steel, high-speed steel, high-strength steel, stainless steel, and heat-resistant alloys. Synthetic diamonds can be produced through two primary methods: the High-Pressure High-Temperature (HPHT) method and Chemical Vapor Deposition (CVD).
Novel Abrasives
Ceramic Alumina Abrasives (SG abrasives) are prepared using a sol-gel process and offer advantages such as high strength, excellent toughness, and superior self-sharpening properties. Agglomerated Abrasives (also known as polycrystalline-like abrasives) are formed by bonding numerous fine-grained abrasive particles together using a binder; they are characterized by their long service life and consistent, uniform material removal rates.
Other Functional Abrasives
CMP (Chemical-Mechanical Polishing) slurries utilize nanoscale abrasive particles-such as silica, ceria, and alumina-for precision polishing applications, notably in semiconductor chip manufacturing.
