A critical review on functionally graded coatings: Methods, properties, and challenges

Improvement of Tribological Performance of TiAlNbN Hard Coatings by Adding AlCrN

“…Careful observations showed that no significant peeling-off phenomenon occurred, which indicated that both the TiAlNbN and multilayered TiAlNbN/AlCrN samples had high adhesion strength, which was important for the tribological applications [ 38 , 39 ]. To improve the adhesion strength between the hard nitride coating and soft metallic substrate, functionally graded materials (FGMs) can be introduced as a transitional layer in coating systems, known as functionally graded coatings (FGCs) [ 40 ]. In recent years, FGCs have played a vital role in thin film and coating engineering applications due to their distinctive features through graded characteristics.…”

Adaptive Control of the Atmospheric Plasma Spray Process for Functionally Graded Thermal Barrier Coatings

“…Figure 3 shows the scheme for the adaptive control process to get the mean normal distributions of the NiCrAlY and the ZrO 2 particles that produce the desired MPSs in the observation window. At the start of the process (t � 0), when only NiCrAlY powder is injected, values of parameters V (1) inj,0 , d (1) y,0 , P 0 , Q 0 and I 0 are found from the response functions given by ( 20) and (21). Tese are used to determine (i) the initial estimates of the controller gains from the MR-MRACs using (18), (ii) the injection parameters V (1) inj and d (1) y from (10), and (iii) the process parameters P, Q and I from (4) that are input to the software LAVA-P. At time t � 100 ms, the injection of the NiCrAlY particles starts, and its mass injection rate is decreased after every 100 ms interval while that of the ZrO 2 increased.…”

“…(d (j) y ) 2 }. In equations (20) and (21), each variable has been normalized to have a value between 0 and 1. Te estimated coefcients of the response functions are listed in Table 3.…”

“…Table 4: Comparison of desired outputs for the NiCrAlY and the ZrO 2 powders with those found from LAVA-P using the process parameters obtained as solutions of equations ( 20) and (21). Desired outputs Process parameters from equation ( 20) and ( 21)…”

Compositionally graded crystals as a revived approach for new crystal engineering for the exploration of novel functionalities

“…In most polycrystalline FGMs, a continuous composition gradient from one material to another across a heterointerface can reportedly suppress abrupt changes in mechanical properties at the interface, leading to improvement in the joining characteristics between metals and biomaterials, among other benefits. 3,4 A detailed insight into FGMs was recently provided by M. Sathish et al 5 In contrast, CGCs are crystalline materials, whose composition is continuously graded by processes, such as the partial substitution of a certain site in the unit cell of single crystals, while maintaining almost the same crystal structure. The first attempt of using CGCs was for the development of new compound semiconductor devices based on (AlGa)As that aimed to improve the performance of devices employing them, such as bipolar transistors, 6 laser diodes, 7 and solar cells.…”