Alkaline water electrolysis is currently the most promising approach to produce hydrogen. However, a main limitation for large-scale application originates from the significant energy loss caused by the coverage of bubbles on the electrode surface. Here, pore-graded Ni electrodes with a positive and negative gradient porous structure that boosts the desorption and release of gas bubble are reported, resulting in a greatly advanced mass transference. The electrodes are obtained from a blend of Ni and Al via high-pressure cold spray. The gradient porosity is realized by varying the addition of Al and chemical etching. As-sprayed electrodes are annealed to eliminate the residual stress and strengthen the adhesion of layers, hence improving their durability. As a result, the electrode with a positive pore-graded structure exhibits a better HER/OER performance when tested with a carbon rob counter electrode. Notably, when tested with an annulus counter electrode of Nickel foam, the electrode with a negative pore-graded structure achieves minimal HER/OER overpotential, outperforming other porous electrodes. This is benefited from improved bubble removal and mass transference capability. All prepared electrodes showed an excellent stability that after 500 cycles of HER/OER test without a large potential fluctuation.

Increasing operating temperature plays a critical role in improving the thermal efficiency of gas turbines. This paper assesses the capability of advanced thermal barrier coatings being developed for use in 1700 °C class gas turbines. Parts sprayed with these coatings were evaluated and found to have excellent durability and long-term reliability.

This study assesses the durability of superhydrophobic surfaces that possess a scalable architecture similar in morphology to branching or corymbose coral. In the experiments, electrolytic copper powders with a coral-like morphology are cold sprayed onto metal, ceramic, and glass substrates, forming a textured copper layer with a structural hierarchy based on the morphology of the powder. After cold spraying, a flame treatment is applied, creating a porous layer of Cu 2 O over the pliable Cu surface, which further increases roughness. As a final step, a fluoroalkyl silane spray is applied to reduce surface energy. It is shown that the fluorinated surface retains its excellent water repellency after cyclic bending and folding, sand-grit erosion, knife-scratching, and even heavy loading with simulated acid rain. It also retains its adhesion to glass (17 MPa), ceramic (12 MPa), and metal (34 MPa) substrates.

The aim of this work is to find a path toward a thermal barrier coating (TBC) that is more thermally stable and less thermally conductive than current 8YZS coatings. The concept of dual-phase composite ceramics is proposed in an effort to combine the desirable attributes of unique phase constitution, low conductivity, and high ceramic fracture toughness. In addition, efforts are made to optimize the spraying process for low-k ceramic topcoats by controlling the effect of key parameters on porosity, deposition rate, and deposition efficiency. Isothermal oxidation and thermal cycling tests are conducted to evaluate the performance of the low-k TBCs with promising results.

High volume production of a consistent, repeatable coating on the internal diameter of surfaces has been a challenge for engineers for many years. Ford Motor Company and Flame Spray Industries, Inc. have developed a Plasma Transferred Wire Arc (PTWA) process and method of applying a wear resistant thermal spray coating on the internal surfaces of aluminum engine cylinder bores. For this automotive application, many challenges existed, including: achieving coating adhesion capable of passing long term engine durability testing, obtaining optimum materials performance and wear resistance, and developing a low cost thermal spray process that would be capable of high volume manufacturing. A novel fluoride based flux surface preparation technique utilizing a non-hazardous chemical solution was developed. This allows a NiAl bond coat to be applied to a non-roughened aluminum surface, yielding high bond strengths with the consistency necessary for high volume production. Process and materials development produced a cylinder bore coating using inexpensive low carbon steel wire feedstock that resulted in a coating with less than 2% porosity. After completing a detailed materials testing program, it was determined that using low carbon steel wire feedstock with compressed air atomizing gas formed a unique thermal spray coating system consisting of an iron/iron oxide (Fe/FeO) structure that exhibited excellent tribological properties while maintaining compatibility with existing piston ring pack materials. The PTWA thermal spray process was designed to operate in a turnkey environment in excess of 100 hours before requiring maintenance or replacement of consumable components. To fully test this process, Ford completed a production prove out including extensive dynamometer and fleet engine testing. The PTWA process proved to be production capable while producing coated aluminum block engines that accumulated over 3 million miles of fleet vehicle tests with zero coating failures. The test engines also exhibited excellent performance including piston and ring wear, power output, oil consumption, and vehicle emissions.