Mullite coating

For better understanding of the CVD phase diagrams, examples based on single component system such as tungsten carbide coating and multi-component system such as mullite coating are discussed below for various process conditions. 

Similarly, CVD phase diagrams for the mullite coatings from the AlCl3-SiCl4-C03-H3... 

Fig. 8 Scanning electron micrograph of the cross-section of a typical mullite coating on SiC using AlCIg-SiCI -COj-H system at 950°C and 75 torn...

Fig. 9 (a) Cross-sectional TEM micrograph of CVD mullite coating on SiC with diffraction patterns... 

Fig. 15 The effect of substrate on the nucleation and growth of mullite coatings using a the gas...

FIGURE 12.9 (a) SEM of a sol-gel ZrOj coated SiC fiber reinforced glass-coMiic. (b) TEM detail of the SiC-mullite coating interface see the elongated rnnUite crystals (1 = 5-10 nm). 

Mulpuri PD, Sarin VK (1996) Synthesis of mullite coatings by chemical vapor deposition. J Mater Res 11 1315-1324... 

The experimental thermal load consisted of a line heat flux focused along the center of the specimen. The specimen geometry was a multi-layered beam consisting of a mullite coating and intermediate layers which were composed of mixtures of mullite and CoCrAlY (the bond coat material). The resulting fracture mode was multiple surface cracking formed in the region near the thermal load. 

H2O environment, leading to cracking and coating recession [72, 73]. Conversely, CVD mullite coatings, characterized as high purity and fully crystalline, appeared to be stable in similar environments [74]. 

Ceramic 92% a-Al Oj, Positive-image, no wash 18% mullite coat ... 

Heimann, R.B., Pentinghaus, H.J., and Wirth, R. (2007) Plasma-sprayed 2 l-mullite coatings deposited on aluminium substrates. Eur. J. Mineral, 19, 281-291. 

Mullite-coated SiC exhibits substantially improved behavior in Na2S04-induced cor-... 

Figure 7-39. Micrograph of plasma sprayed mullite coating on SiC coupon. (Jacobson et al., 1994.)...

---