Application and characteristics of talcum powder in food grade grease
Food safety has always been the focus of people’s attention. There are many factors affecting food safety, among which the pollution caused by the leakage of lubricating materials in food equipment is one of the important reasons. Food-grade grease is widely used in key transmission parts of food processing equipment such as bearings, chains and guide rails, and the lubricating performance of grease mainly depends on the additives used.
In view of the guarantee of the safety of food-grade grease, non-toxic and harmless are the primary considerations when selecting additives. As a food additive, food-grade talc powder is often used in food flow aids and mold release; because of its good lubricating properties, it also has certain applications in the field of tribology, such as coating talc powder on protective clothing to Reduce skin damage of medical staff during COVID-19; in addition, talc powder in lubricating oil has excellent anti-friction properties, which can better reduce the wear of cast iron equipment.
The composite aluminum-based grease was prepared by white oil and thickener, and the effect of the mass fraction of food-grade talcum powder on the tribological properties of the grease was investigated. The results showed that:
(1) Talc powder can improve the thermal stability of the composite aluminum-based grease, and the extensional decomposition temperature of the base grease is significantly lower than that of the grease containing talc powder;
(2) Talc powder can improve the tribological properties of composite aluminum-based grease, that is, improve the stability of the friction process, reduce the friction coefficient and wear volume; When the mass fraction of talcum powder is 1.0%, the average friction coefficient and wear volume are the smallest; Polishing plays an effective anti-friction and anti-wear effect;
(3) The lubricating grease with 1.0% talc powder is most likely to be applied to food equipment and other fields.
(4) Talc powder is a layered silicate, which can be adsorbed on the surface of the friction pair during the friction process, which is equivalent to the sliding of a “sliding bearing”, thereby reducing friction and reducing wear.
(5) From the perspective of the thermal stability of the grease, when the degradation termination temperature is reached, the remaining weight of the grease sample containing talcum powder is higher than that of the base grease. This is because the main components of talc powder are MgO and SiO2, and the heat of SiO2 Good stability, can improve its thermal stability. Since a large amount of heat is easily generated during the friction process, SiO2 with better thermal stability tends to stay in the gap of the friction pair. Due to the roughness of the surface of the steel plate, the real contact area between the steel ball and the steel plate is small, and it bears high contact stress at the beginning of the friction process, which is easy to generate large friction and creates grooves on the surface of the wear scar, so some talc powder (mainly SiO2) can repair the gully produced on the surface of the wear scar during the friction process, thereby increasing the contact area between the friction pairs and reducing the contact stress between the friction pairs; at the same time, SiO2 is a commonly used polishing material, so a small amount of SiO2 can A micro-polishing effect is produced on the surface of the friction pair, thereby achieving the effect of reducing friction and reducing wear.