Search

This study aims to minimize the mechanical, chemical and thermal damages on the blades of a compressor used in aerospace engines by developing a superhydrophobic coating on the blade surface. In the absence of any information in open literature for the fabrication of such coatings, an one-step plasma spray process was implemented. For this, a well mixed powder of Ni and Ti was used as feedstock material. The superhydrophobicity characteristic of the coating was confirmed by the measurement of the contact (165°) and sliding angles (8 ± 1°) by the sessile drop technique. The adhesion test of the coating showed the high force of adhesion at the interface with a failure limit of 40.85 MPa. Furthermore, the abrasion test depicted an excellent abrasion resistance of the coating. These two investigations indicated that the coatings had a very high mechanical durability. The coatings also showed an excellent thermal stability up to 400 °C. Beyond this temperature (at 600 and 900 °C), the superhydrophobic characteristic changed for hydrophobic. The pH and corrosion tests were also performed to assess the chemical stability of coatings. They showed that the coatings retained the superhydrophobic property for pH ranging between 9.5 and 2.4. Beyond this range, at pH = 10 and pH = 2, the contact angles were 138° and 143°, respectively. In addition, the coatings exhibited a better corrosion resistance than the substrate and coatings developed by using other deposition techniques.

NiTi shape-memory alloy coatings were deposited by atmospheric plasma spray (APS) on mild-steel substrates and their mechanical properties such as hardness (Vickers’s microhardness), adhesion strength (ASTM C-633), and wear resistance (solid particle erosion) analyzed. The physical characteristics of the surface and interface of the as-deposited coating were investigated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and x-ray diffraction (XRD) analysis. Also, the as-deposited coatings were exposed to airborne particle erosion to investigate their wear behavior for different erodent impact angles. The correlations between various plasma parameters and the erosive wear resistance and mechanical properties of the coating were established. In addition, the surface morphology of the eroded surface was investigated by scanning electron microscopy to analyze the different wear mechanisms (plastic deformation, crater formation, splat boundary pile-up, and lip formation) occurring on the surface.

In the current review, the failure analysis of gas turbine blades and to overcome those failures the development of materials have been discussed. The properties of a gas turbine blades should have exhibit have been reported in the current review. In addition to the above, the importance of coating in gas turbine blade has been listed. After the brief investigation of the failure analysis and materials developed it is observed that still there are some properties to be developed to obtain an optimum gas turbine blade.

In the past few years, there is a global need for engine manufacturers to give high performance and long durable engines by using good quality of materials. Previously, engine manufacturers have applied protective coatings to increase the life and performance of the aero engine. Today, a wide variety of parameters in environmental and material design challenges together with the component design of engines demanded towards the economic protective coating processes. In an aero engine, the protection against wear inside the inner surface casing is a great challenge. Present work is focused on the study of improvement of abradable resistance on aero-engine inner case materials by using a plasma spraying technique. Different wt% of (Al + Ni+(h)BN) homogenized powder mixture and sodium silicate as an inorganic binder is used for spraying. The surface property analysis of plasma sprayed coating has been characterized using, optical microscopy, scanning electron microscopy, X-Ray diffraction and Vicker hardness tester. It was found that the coating using (Al + Ni+(h)BN) homogenized powder is successful in finding optimum stand-off distance which can increase the life span of the aero-engine casing.

The objective of this is to optimize surface properties by an economical process. Nowadays researches are going on the capacity of industrial waste for coating. Fly-ash appears as a major waste suitable for coating from recent research. Mostly it consists of iron, oxides of silicon, aluminium and titanium. First of all, fly-ash mixed with quartz and ilmenite before spraying which is easily available and also low in cost preferable for giving protection against abrasive wear, erosion etc. Atmospheric Plasma spraying gives quality coatings and can be sprayed approximately on any substrates. This type of industrial waste as coating material decreases the cost of plasma spray coating. Composition of fly-ash + quartz + illmenite is deposited on mild steel and copper substrate by APS technique between 11 and 21 kW power. Then the characterization of the coated surface was carried out by particle size analyzer, coating pull out method, micro-hardness tester, XRD analysis and scanning electron microscope (SEM). This work establishes the potential of fly-ash + quartz + ilmenite for coating, which is a low-grade mineral and readily available from industrial waste.

This paper deals with the casing surface and blade tip clearance in an axial flow compressor in aero-engines. The clearance in between the tips of the blade and the casing surface should be optimized by considering the thermal and internal expansion as well as changes in concentricity due to shock loading events, to prevent catastrophic tip to casing contact. These parameters play a significant role in the efficiency enhancement of aero-engine. Generally, In case of shock loading, the tip of the blade severely damages the casing surface, which is a primary concern of an aero-engineer. To protect the tip as well as the casing, there is a coating developed called abradable coating, which is not only to allow for closer clearances. But to automatically adjust clearances, in-situ, to accept physical events and thermal variation that may be found during its exploitation. An abradable coating must have sufficient strength and hardness to resist the rigidness of aero-engine handling during assembly, transportation, and exploitation. At the same time, it must be soft enough to allow the axial flow compressor rotor blades to cut through it easily without getting pilled off in lumps. The current investigation is done to optimize the plasma coating parameters such as Powder feed rate, Plasma power, powder grain size, Gun Velocity, spray distance, Argon/hydrogen ratio, and their pressure, etc.

In the current investigation, an equiatomic mixture of Ni and Ti was coated on the mild steel substrate by atmospheric plasma spray coating technology. The coating process was performed by varying the primary gas flow rate and plasma arc current process parameters. The microhardness and adhesion strength of the coating was evaluated after successful coating operation. The variation of microhardness and adhesion strength with primary gas flow rate and plasma arc current was observed. The results revealed that the microhardness varies directly with plasma arc current and primary gas flow rate. The enhancement in molten fraction and pinching effect was resulted due to increase in the primary gas flow rate that leads to the increase in microhardness. Furthermore, the enhancement in enthalpy and reduction in diffused air due to increase in arc current resulted in an increment in microhardness. The increase in plasma velocity and molten fraction of the particles resulted in better adhesion strength of the coating at higher gas flow rate and arc current. The microstructures of the coatings developed at higher and lower parameters support the above-stated relation.

Type 304 stainless steels have profound application in engineering including springs, kitchen equipment, auto wheel covers, hose clamps, truck bodies, exhaust manifolds, storage tanks, piping and pressure vessels, etc. AISI 304 is rolled/deformed uniaxially to reduce the thickness to 20, 40, 60% of the initial thickness using rolling machine (notation CW00, CW20, CW40, CW60). The magnetic character of type 304 stainless steel was measured in terms of percentage martensite content using feritscope after cold rolling. It is observed that the cold work structure forms high dislocation density regions or tangles, which further develop onto tangled network; therefore, higher cold worked material has higher slip bands or planes. As the amount of percentage deformation increases, martensite formation increases, and hence, the magnetic nature increases. With increase in cold work, hardness also increases due to the formation of martensite in different systems of slip planes. Again, it is observed that corrosion test in H2SO4 and KSCN solution highly affects the slip planes.

Nanocoating is a part of nanotechnology that efficiently gives resistance to corrosion and wear along with formation of hydrophobic surface. This chapter explains different corrosion processes and prevention for thin coating, materials use for nanocoating, and the variety of processes for nanofilm development. Application of nanocoating at different industries is described in the direction of corrosion. Advantages and limitations are also discussed for specific applications.

Vacuum carburizing is carried out on Aero engine gears to obtain high case depths of the gear teeth to resist wear and tear. The depth of carburizing has to be uniform and consistent to achieve long life of the aero engine gears. The case depth is sensitive to a lot of parameters involved in the process of case carburizing. It is necessary to first identify the significant factors and then optimize it through repetitive iterations. Design of Experiments has been utilized to identify critical to quality parameters and evolutionary optimization techniques have been used to fine tune their values.Vacuum carburizing is carried out on Aero engine gears to obtain high case depths of the gear teeth to resist wear and tear. The depth of carburizing has to be uniform and consistent to achieve long life of the aero engine gears. The case depth is sensitive to a lot of parameters involved in the process of case carburizing. It is necessary to first identify the significant factors and then optimize it through repetitive iterations. Design of Experiments has been utilized to identify critical to quality parameters and evolutionary optimization techniques have been used to fine tune their values.

This chapter describes the fiber reinforcement in metal, ceramic, and polymer matrix nanocomposites. Each part of the aerocraft is explained with respect to their suitable nanocomposite materials. Turbine engine always uses the metal matrix and ceramic matric nanocomposite for its efficiency enhancement. Polymer matrix nanocomposite is the suitable material for high-strength structural frames, nose, vertical, and horizontal stabilizers. Fiber-reinforced polymer also plays a major role in lightweight aeroplane manufacture.

In the current investigation, an elemental blending of equiatomic Ni and Ti powder was considered to spray on mild steel by the atmospheric plasma spray process. The results revealed that the coating developed with 120 mm stand-off distance (SOD) has better mechanical properties such as microhardness and adhesion strength. Again, SOD predominantly influences the formation of intermetallics (NiTi, Ni3Ti, Ti2Ni, and TiO) that helps to enhance the microhardness (683.85 HV) as well as the mechanical interlocking and chemical bonding that is solely responsible for the high adhesion strength (43.17 MPa) of the coating. The failure analysis of the coating developed at too high and too low SOD revealed that rapid expansion of gas stream, reduction in enthalpy of particles, improper heat transfer, burning of splat, agglomeration of particles during flight, and oxidation are the key factors responsible for the reduction in mechanical properties of plasma-sprayed Ni-Ti alloy (NITINOL) coatings. In addition to the above, the solid particle erosion analysis revealed the increase in brittleness of the coating with increasing in SOD. The surface morphologies of the eroded surface depict various erosion mechanisms at both 45° and 90° impingement angles such as chip formation, lip formation, plastic deformation, scratches, etc.