Laser Engineering Net Shaping Method in the Area of Development of Functionally Graded Materials (FGMs) for Aero Engine Applications - A Review

Abstract

Modern aero engine components are subjected to extreme conditions were high wear rate, excessive fatigue cycles, and severe thermal attack are inevitable. These aggressive conditions reduce the service life of components. Its generic effect is magnified in the light of understanding the fact that aero engine parts are highly sensitive to functional and dimensional precision therefore, repair and replacement are great factors that promote downtime during operation. Hard thermal barrier coatings have been used in recent times due to their optimized properties for maximum load bearing proficiency with high temperature capability to meet performance and durability required. Nevertheless, less emphasis is being given to the coating-substrate interaction. Functionally graded structures have better synergy and flexibility in composition than coatings, giving rise to controlled microstructure and improved properties in withstanding acute state of affairs. Such materials can be fabricated using Laser Engineered Net Shaping LENS™ , a laser-based additive manufacturing technique. LENS™ offers a great deal in rapid prototyping, repair, and fabrication of three-dimensional dense structures with superior properties in comparison with traditionally fabricated structures. The manufacture of aero engine components with functionally graded materials, using LENS™, can absolutely mitigate the nuisance of buy-to-fly ratio, lost time in repair and maintenance, and maximize controlled dimension and multi-geometric properties, enhanced wear resistance, and high temperature strength. This review presents an extensive contribution in terms of insightful understanding of processing parameters and their interactions on fabrication of functionally graded stainless steel, which definitely influence the final product quality.

High Entropy Alloys for Aerospace Applications

“…The laser scan speed offers the laser powers enough heating energy to melt the high entropy alloy powders and slower scan speed ensures a longer period to melt the powder layer completely. Therefore, the laser scan speed and the laser power will determine the energy density within the melt pool [33].…”

Functionally graded materials classifications and development trends from industrial point of view

“…Optimization of processing parameters (such as distance between gun and substrate, feed-rate, carrier gas composition) can differ between the two components of the FGM structure [41,[106][107][108] Laser deposition High accuracy due to laser control Selectively deposited material reduce the post-process machining/finishing Uneconomical for bulk FGM Only produce discrete structures Relatively high residual stresses requires post heat treatment [109][110][111][112][113][114] Vapour deposition processes Layers can be in nano/micro range Graded structure easy to control simply by varying the composition of the gas phase Attention must be paid to subsequent heat treatments to avoid inter diffusion between the substrate and the graded film [115,116] Infiltration Layers produced can be very thin Structure has a good mechanical strength Suitable method for FGMs containing phases of very different melting points Difficult to control process Graded preform should have sufficient porosity for the liquid metal to penetrate and get solidified [117][118][119][120] The properties of FGMs containing orientation gradient change as a result of a change in particles orientation, not due to a phase ratio or size change. There are different methods that can be used to achieve orientation gradient in FGMs.…”

“…The composition type of FGM gradient depends on the composition of the material, which varies from one substance to another, leading to different phases with different chemical structures. These different phases of production depend on the synthetic quantity and the conditions under which the reinforced materials are produced [41]. During the solidification process, the microstructure type of the FGM gradient can be achieved so that the surface of the material is extinguished.…”

Lattice Structures and Functionally Graded Materials Applications in Additive Manufacturing of Orthopedic Implants: A Review

“…Although this technique has not been applied in the biomedical realm, it suggests a direction for improving the hardness of articulating surfaces (a) (b) ( c) Figure 2. Classification of functionally graded material (FGM) according to (a) composition [93]; (b) microstructure [92]; (c) porosity [94]. Figure 2.…”

“…Figure 2. Classification of functionally graded material (FGM) according to (a) composition [93]; (b) microstructure [92]; (c) porosity [94].…”