Effect of negative thermal expansion additives on the thermal and tribological properties of mineral casting material

Abstract Mineral castings are used in the fabrication of precision measurement and machining platforms due to their favorable material properties. However, their high resin contents result in high coefficients of thermal expansion (CTE) and wear rates. This study introduces a novel mineral casting material incorporating β‐eucryptite, an additive with negative thermal expansion (NTE). The effects of varying β‐eucryptite contents on the thermal expansion and tribological properties of the mineral casting were investigated. Results demonstrated that the addition of β‐eucryptite reduced the CTE of the mineral casting by 42.21% and achieved a low thermal diffusivity (Dmin = 0.61 mm²/s). Additionally, it decreased the wear rate by 73.83%. The experiment verified the effect of thermal expansion on the wear performance of materials. By reducing the expansion caused by frictional heat, the variation in surface roughness at the contact interface was minimized, leading to a reduction in wear. Highlights The addition of β‐eucryptite reduces the CTE by 42.21%. Thermal diffusivity of mineral castings is 96.87% lower than that of cast iron. The addition of β‐eucryptite reduces the wear rate by 73.83%. Low coefficient of thermal expansion reduces the wear rate.