Iranian Journal of Materials Science and Engineering

• Zr-doped NiAl coatings were prepared by aluminizing and then Zr sputtering.
• Zr decreased Al outward diffusion during oxidation and resulted in less oxide layer thickness.
• The coating of 300 nm Zr-NiAl exhibits the best spallation resistance.

 Particularly mullite zirconia composites are materials with important technological applications due to their good properties such as toughness, chemical stability, and high-creep resistance. In practice they are employed in the glass industry and where high chemical and corrosion resistance are required.
 
The purpose of the current research was to investigate the effect of La2O3 additive in the reaction sintering process of conventional raw materials on thermal, microstructure and mechanical properties of mullite–zirconia composites.
 
Usually, mullite zirconia composites can be obtained by various methods such as direct powder compact of mullite and zirconia, reaction sintering of alumina, silica and zirconia; reaction sintering of alumina and zircon. Similarly, various researchers have studied the effect of different additives on the formation and sintered characteristics of the mullite-zirconia composite. It was found that the addition of lanthanum oxide decreased the densification temperature and significantly improved the thermal shock resistance of the mullite–zirconia composites. In addition to the mullite zirconia composites studies containing La2O3 originality of our work is to observe the effect of La2O3 addition to kaolinite, alumina and zircon mixture synthesized from conventional raw materials and so to form a new reference and field of interest.