For the surface treatment of microwave oven baking trays, optimizing the glaze formulation is the core method to improve scratch resistance and acid/alkali resistance. Traditional glazes are prone to cracking and peeling under high-temperature microwave environments due to uneven thermal stress or chemical corrosion. However, by adjusting the raw material ratio and process parameters, the physicochemical stability of the glaze can be significantly enhanced, meeting the dual requirements of durability and safety for microwave oven baking trays.
Improving the scratch resistance of the glaze requires starting with raw material selection and structural design. High-hardness raw materials such as quartz and alumina can increase the wear resistance of the glaze. Their crystal structure forms a dense network after high-temperature sintering, effectively resisting external scratches. Simultaneously, the appropriate introduction of needle-like crystal raw materials such as wollastonite or zircon can form an interwoven support structure in the glaze, dispersing stress and reducing crack propagation paths. For example, the addition of wollastonite not only increases the hardness of the glaze surface but also lowers the firing temperature, reducing energy consumption. Furthermore, by controlling the ball milling fineness of the glaze, the raw material particles are evenly distributed, avoiding rough glaze surfaces caused by excessively coarse local areas, further reducing the risk of scratches.
Optimizing acid and alkali resistance requires focusing on the chemical inertness of the glaze layer. Traditional glaze layers are prone to surface corrosion when in contact with acidic or alkaline substances due to ion exchange or dissolution reactions. However, by adjusting the ratio of alkaline oxides to acidic oxides in the glaze, a stable glassy phase structure can be formed. For example, increasing the content of zinc oxide or magnesium oxide can improve the glaze layer's buffering capacity against acids and alkalis, while reducing the proportion of easily soluble ions such as sodium and potassium, preventing the glaze layer from thinning or peeling off over long-term use. Furthermore, introducing fluxes such as fluorides or borates can lower the glaze layer's firing temperature, reducing porosity caused by raw material decomposition at high temperatures, thereby improving the glaze layer's density and impermeability.
Glaze layer formulation optimization also needs to consider microwave adaptability. Microwave oven baking trays need to be heated rapidly and evenly in a high-frequency electromagnetic field. If the glaze layer contains metallic components or conductive impurities, it may cause localized overheating or even sparks, endangering safety. Therefore, the formulation should avoid using metal oxide colorants such as iron and copper, and prioritize raw materials with better microwave transparency such as cobalt and nickel. Simultaneously, by adjusting the glaze thickness and sintering process, it's crucial to ensure the thermal expansion coefficients of the glaze and the substrate material (such as ceramic or enamel) are matched, preventing cracking or peeling due to temperature differences. For example, employing a staged sintering process—first removing organic matter from the glaze at a low temperature, then promoting glass phase formation at a high temperature—can significantly improve the bonding strength between the glaze and the substrate.
Improving the surface treatment process is equally critical. The glazing process should utilize spraying or dipping methods to ensure a uniform glaze coverage of the baking tray surface, avoiding performance differences caused by localized excessive thickness or thinness. The firing temperature must be strictly controlled above 1250℃ to ensure the glaze fully melts and forms a smooth surface, while controlling the firing time to prevent over-firing or under-firing. Furthermore, rapid cooling after firing is necessary to fix the crystal structure in the glaze and reduce the impact of residual stress on scratch resistance.
In practical applications, the optimized glaze formulation can significantly improve the overall performance of microwave oven baking trays. For example, one company increased the alumina content in the glaze and adjusted the firing process, raising the Mohs hardness of the baking tray glaze from 5 to 7, improving scratch resistance by 30%. Simultaneously, by optimizing the proportion of alkaline oxides, the glaze showed no significant corrosion after immersion in an acidic or alkaline environment with a pH range of 2-12 for 24 hours, improving acid and alkali resistance by 50%. These improvements not only extend the lifespan of the baking tray but also reduce the risk of food contamination, meeting the stringent safety and durability requirements for microwave oven baking trays.
Glaze formulation optimization is an effective way to improve the scratch resistance and acid/alkali resistance of microwave oven baking trays. Through comprehensive optimization of raw material selection, structural design, process improvement, and microwave adaptability adjustments, glazes with high hardness, strong corrosion resistance, and microwave safety can be prepared, providing technical support for the high-quality production of microwave oven baking trays. In the future, with advancements in materials science and surface engineering technology, glaze formulation optimization will further drive the development of microwave oven baking trays towards greater efficiency and environmental friendliness.
