The hardness of the ceramic tool is RA 93 ～ 94, the transverse breaking strength is (10 ～ 11) × 104psi, which is about half of the carbide, and the hardness at high temperature is very high. The hardness is still not reduced at about 2000ºF, so the cutting speed is 2 ～ higher than the carbide. 3 times. Due to particle size, purity, manufacturing methods and other factors, ceramic inserts are only suitable for cutting cast iron.
When ceramic tools cut cast iron, a layer of low-shear-strength graphite is formed on the chip surface, which does not cause dents like tungsten carbide tools. When cutting hard steel, because the welding area between the chip and the tool is very small, the dent on the tool surface will also be less than that of tungsten carbide. Due to the brittleness of ceramic tools, peeling is easy to occur when cutting mild steel under conditions that generate chipping edges (BUE) or discontinuous cutting. When ceramic tools cut aluminum or titanium alloys, because these materials have a very high affinity for oxygen or oxidized surfaces, the chips and the tool will be strongly combined, thus accelerating the tool wear rate.
The improvement of ceramic tools relies on the innovation of different additives and processes, and gradually meets the cutting requirements. For example, ceramics that are traditionally pressed and sintered at room temperature. After sintering is completed, HIP sintering can be used to eliminate sand holes left by sintering shrinkage and to make ceramics. The structure itself becomes denser due to heat and pressure again, and the toughness and strength are better.