In the relentless pursuit of efficiency, the energy sector is always on the lookout for materials that can withstand the harshest conditions. A recent study published in the journal Materials Engineering (Cailiao gongcheng) has shed new light on a promising candidate for protecting heavy-duty gas turbines. The research, led by HE Lei from Shanghai Electric Gas Turbine Co., Ltd., explores the sintering resistance properties of a novel thermal barrier coating, LaMgAl11O19 (LMA), comparing it to the industry-standard Yttria-Stabilized Zirconia (YSZ) coatings.
As gas turbines push the boundaries of temperature to increase efficiency, traditional YSZ coatings struggle to keep up. “The gas inlet temperature of heavy-duty gas turbines keeps increasing,” HE Lei explains, “and traditional YSZ coatings can’t service above 1200°C.” This is where LMA coatings come into play. Fabricated using the air plasma spray method, LMA coatings have shown promising results in static oxidation tests conducted at 1100°C and 1300°C.
The study, which delved into the porosity, microstructure, and phase transformation processes of both LMA and YSZ coatings, revealed intriguing findings. While the porosity of YSZ coatings decreased with time, LMA coatings exhibited an increase in porosity, which surprisingly enhanced their sintering resistance. “The grain growth in LMA coatings becomes platelet-shaped with time,” HE Lei notes, “which improves their sintering resistance.”
The research also highlighted the phase transformation process in YSZ coatings. Using Rietveld refinement, the team observed a significant decrease in the T′ phase content and an increase in C and M phases over time at 1300°C. This phase transformation leads to volume changes, generating large residual stresses that can cause the coating to fall off.
The implications of this research are significant for the energy sector. As gas turbines continue to operate at higher temperatures, the demand for durable, high-performance thermal barrier coatings will only grow. LMA coatings, with their superior sintering resistance, could pave the way for more efficient and reliable gas turbines. Moreover, the insights gained from this study could inspire further research into advanced materials for extreme environments.
The energy sector is always hungry for innovation, and this study serves as a testament to the power of materials science in driving progress. As HE Lei and his team continue to explore the potential of LMA coatings, the future of gas turbine technology looks brighter than ever. The research, published in Materials Engineering (Cailiao gongcheng), marks a significant step forward in the quest for more efficient and durable thermal barrier coatings.