In this work, CeO 2 -G d2 O 3 co-stabilized ZrO 2 (CGZ) thermal barrier coatings are deposited by solution precursor plasma spraying and the microstructure, phase stability, thermophysical properties, and thermal cycling behaviors of the resulting coatings are investigated and discussed in comparison to conventional 8YSZ coatings.

Strontium zirconate is a candidate material for thermal barrier coatings due to its high melting point, good sintering resistance, and high TCE. One drawback, however, is a phase transition that occurs below 1200 °C , although rare-earth element doping offers a way to suppress it. In this study, SrZrO 3 doped with two rare earth oxides, ytterbia and gadolinia, is deposited by solution precursor plasma spraying and the layers obtained are evaluated before and after heat treatment. The coatings are characterized by two phases, SrZrO 3 and t-ZrO 2 , with interpass boundary structure, nano and microscale porosity, and through-thickness vertical cracks. XRD analysis after heat treatment at 1400 °C for 360 h shows that the two phases are very stable due to the doping of rare-earth elements, which is also shown to reduce thermal conductivity in the as-sprayed deposits by nearly 35%.

Photon Emission Microscopy is the most widely used mainstream defect isolation technique in failure analysis labs. It is easy to perform and has a fast turnaround time for results. However, interpreting a photon emission micrograph to postulate the suspected defect site accurately is challenging when there are multiple abnormal hotspots and driving nets involved. This is commonly encountered in dynamic emission micrographs that are caused by open defects in digital logic. This paper presents a methodology incorporating layout-aware trace analysis and post schematic extraction with test bench analysis to enhance the diagnostic resolution on the suspected defective net(s).

The in-flight particle temperature and velocity are very important factors that determine the deposition characteristics and coating qualities in plasma spray. Therefore, predicting the in-flight particle temperature and velocity with spray conditions is benefit to control the prepared coating qualities. In the present study, a steady-state 3D model was used to calculate the gas flow field of a plasma jet. The plasma gas temperature and velocity profiles applied to the plasma jet as the boundary conditions were obtained with our previous studies of plasma arc behaviors inside plasma torch. After obtained the gas temperature and velocity of the plasma jet, the in-flight particle trajectories, temperature, and velocity were investigated with numerical calculation method. Also the inflight particle temperature and velocity were verified by experimental measurements.

This study evaluates a method for producing Gd 2 Zr 2 O 7 /SrZrO 3 , a ceramic-matrix composite considered for use as a thermal barrier coating. GdZrO/SrZrO powders are synthesized by co-precipitation, then cold pressed and sintered to form the bulk composite material. Phase stability of the powder and bulk material is assessed by X-ray diffraction and several bulk material properties are determined, including microhardness, Young’s modulus, fracture toughness, thermal expansion coefficient, heat capacity, thermal diffusivity, and thermal conductivity. The results are presented and discussed.

This work demonstrates the fabrication of a hydroxyapatite (HA) composite material for potential use in biomedical implant applications. A composite powder is prepared by introducing graphene oxide (GO) and F- ions, which are incorporated in the HA crystal structure via in-situ chemical synthesis. The powder is consolidated through spark plasma sintering, resulting in a biocomposite (GO-FHA) material that is mechanically stronger and more chemically stable after implantation than HA. The addition of GO and partial substitution of F- also promote osteoblast proliferation as in-vitro bioactivity tests show.

The La 2 Zr 2 O 7 /SrZrO 3 composite with a mol ratio of 1:2 named (La 0.5 Sr 0.5 )ZrO 3.25 (LSZ) was in-situ synthesized by co-precipitation method using ammonia and ammonium oxalate as precipitants. The synthesized LSZ powder showed good phase stability not only from room temperature to 1400°C but also at higher temperature of 1450°C for a long period, as analyzed by thermogravimetry, differential scanning calorimetry and X-ray diffraction, respectively. The bulk LSZ with relative density >95% was prepared by pressureless sintering at 1500°C for 2 h and spark plasma sintering (SPS) at 1300°C for 5 min, respectively. The fracture toughness of the bulk LSZ prepared by both pressureless sintering and SPS were 1.80±0.20 MPa·m 1/2 and 1.95±0.09 MPa·m 1/2 , respectively, which are higher than that of both bulk SrZrO 3 and La 2 Zr 2 O 7 . The coefficients of thermal expansion (CTEs) of the bulk LSZ were 8.4-9.5×10 -6 K -1 in a temperature range of 200-1200°C, which are higher than that of La 2 Zr 2 O 7 but lower than that of SrZrO 3 . The thermal conductivity of the bulk LSZ prepared by pressureless sintering was ~1.1 W·m -1 ·K -1 at 1000°C, which is lower than that of both bulk SrZrO 3 and La 2 Zr 2 O 7 . The LSZ composite is considered as a promising thermal barrier coating material.

This study investigates the phase stability and thermophysical properties of Y 2 O 3 and Yb 2 O 3 co-doped SrHfO 3 (SHYY) powder and bulk material along with the phase stability and microstructure evolution of as-sprayed SHYY coatings during annealing. The powder was synthesized by a solid-state reaction at 1450 °C, showing good phase stability up to 1400 °C. Dilatometry measurements revealed no abnormal changes in the coefficient of thermal expansion over a temperature range of 200-1300 °C. The thermal conductivity of the bulk material was found to be 16% lower than that of SrHfO 3 . Free-standing SHYY coatings deposited by air plasma spraying were also tested. The coatings consisted of SHYY and a minor amount of secondary phase Yb 2 O 3 and exhibited good phase stability during heat treatment at 1400 °C for 288 h. Coating samples examined after 216 h still exhibited a columnar microstructure.

Advanced ceramic materials with perovskite structure have been developed for potential applications in thermal barrier coating (TBC) systems in an effort to overcome the properties of the pre-existing ones like 8wt% yttria stabilized zirconia (8YSZ). Y 2 O 3 and Yb 2 O 3 co-doped strontium zirconate with chemistry of Sr(Zr 0.9 Y 0.05 Yb 0.05 )O 2.95 (SZYY) was synthesized using ball milling prior to solid-state sintering, and had a minor second phase of Yb 2 O 3 . The SZYY showed good phase stability not only from room temperature to 1400°C, but also at high temperature of 1450°C for a long period, analyzed by thermogravimetry-differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD), respectively. The thermal expansion coefficients (TECs) of the sintered bulk SZYY were recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrZrO 3 by codoping Y 2 O 3 and Yb 2 O 3 . The thermal conductivities of SZYY were at least ~30% lower in contrast to that of SrZrO 3 and 8YSZ in the whole tested temperature range. The good chemical compatibility was observed for SZYY with 8YSZ or Al 2 O 3 powders after 24 h heat treatment at 1250°C. The phase stability and the microstructure evolution of the as-sprayed SZYY coating during annealing at 1400°C were also investigated in this work.

Advanced ceramic materials of perovskite structure have been developed for potential application in thermal barrier coating systems, in an effort to improve the properties of the pre-existing ones like yttria stabilized zirconia. Yb 2 O 3 and Gd 2 O 3 doped strontium zirconate (SrZrO 3 ) and barium magnesium tantalate (Ba(Mg 1/3 Ta 2/3 )O 3 ) of the ABO 3 and complex A(B’ 1/3 B” 2/3 )O 3 systems respectively, have been synthesized using ball milling prior to solid state sintering. Thermal and mechanical investigations show desirable properties for high temperature coating applications. On atmospheric plasma spraying, the newly developed TBCs reveal promising thermal cycle lifetime above 1300°C.