Oxidation and corrosion protective coatings on graphite are essential for its high temperature applications. In the present work, oxidation protective coating on graphite was achieved with a combination of Y₂O₃ and SiO₂ suspension with NaOH in methanol. Study showed that the optimized composition of the desired coating was Y₂O₃–15 wt% SiO₂ (i.e., 2 g mixture of Y₂O₃ and SiO₂ powder containing 0.3 g of SiO₂ which is 15% of the total powder content if expressed in weight) with 5 M NaOH in 10 mL methanol. This protective coating on graphite was stable up to 1473 K for 30 min in Ar ambient before visible cracks appeared. The compositions of SiO₂: NaOH were varied (5 mmol:5 M, 10 mmol:5 M and 5 mmol:10 M) to examine the roles of these two components in the overall adhesiveness of the coating. SiO₂ and NaOH acted as inorganic binders and formed in-situ intermediate layers during sintering which held Y₂O₃ layer with the graphite surface. The coated graphite blocks and crucibles were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS), differential thermal analysis and thermogravimetric analysis (DTA/TGA) and Fourier transform infrared spectroscopy (FTIR). The oxidation protective nature of the coating was tested by heating the coated crucible at 1273 K for 1-15 h in air atmosphere. The effective adhesion of oxidative coating on graphite was explained.

石墨上的氧化和防腐蚀涂层对于其高温应用至关重要。在目前的工作中，通过将Y ₂ O ₃和SiO ₂悬浮液与NaOH在甲醇中的混合物相结合，在石墨上实现了氧化保护涂层。研究表明，所需涂层的最佳组成是Y ₂ O ₃ –15 wt％SiO ₂（即2 g Y ₂ O ₃和SiO ₂粉末的混合物，其中包含0.3 g SiO ₂（以重量表示，则为粉末总含量的15％），用5 M NaOH在10 mL甲醇中的溶液洗涤。在Ar气氛中，石墨上的这种保护涂层在高达1473 K的温度下稳定了30分钟，然后才出现可见的裂纹。改变SiO ₂：NaOH的组成（5 mmol：5 M，10 mmol：5 M和5 mmol：10 M），以检查这两种组分在涂层的总体粘合性中的作用。SiO ₂和NaOH充当无机粘合剂，并在烧结过程中原位形成了中间层，并保留了Y ₂ O _3。石墨表面的涂层。通过X射线衍射仪（XRD），场发射扫描电子显微镜（FESEM），能量色散X射线光谱仪（EDS），差热分析和热重分析（DTA / TGA）和傅里叶变换对涂层的石墨块和坩埚进行表征红外光谱（FTIR）。通过在空气气氛中将涂层坩埚在1273 K下加热1-15小时来测试涂层的抗氧化性能。解释了氧化涂层在石墨上的有效附着力。