Macor

Macor is the trademark for a machineable glass-ceramic developed and sold by Corning Inc. It is a white material that looks somewhat like porcelain. Macor is a good thermal insulator and is stable up to temperatures of 1000 °C, with very little thermal expansion or outgassing. It can be machined using standard metalworking tools. Macor is the trademark for a machineable glass-ceramic developed and sold by Corning Inc. It is a white material that looks somewhat like porcelain. Macor is a good thermal insulator and is stable up to temperatures of 1000 °C, with very little thermal expansion or outgassing. It can be machined using standard metalworking tools. Macor is made up of fluorphlogopite mica in a borosilicate glass matrix. Its composition is roughly: 46% silica (SiO2), 17% magnesium oxide (MgO), 16% aluminium oxide (Al2O3), 10% potassium oxide (K2O), 7% boron trioxide (B2O3), 4% fluorine (F). Macor has a density of 2.52 g/cm3, a Young's modulus of 66.9 GPa at 25 °C, a specific stiffness of 26.55×106 m2s−2, a Poisson’s Ratio of 0.29 and a thermal conductivity of 1.46 W/(m·K). It has a low-temperature (25 to 300 °C) thermal expansion of 9.3×10−6 K−1. Its compressive strength is 50×103 lb/in2 (~350 MPa). Nominal engineering properties are comparable to borosilicate glass.