TiAl 3 -Al composite coatings are believed to hold promise for extending the service temperature range of titanium alloys used as structural materials. In this study, 0.6 x 40 mm Ti-6Al-4V specimens are coated with a 30 μm thick layer of TiAl 3 -Al by low-temperature HVOF spraying. Cross-sectional imaging shows that the as-sprayed coatings have a dense laminar microstructure and are well bonded to the substrate. Following the initial examination, the coating samples were placed in a muffle furnace, where they were held at 700 °C for up to 1000 h. Mass gain was detected starting at 200 h and remained nearly constant for the remainder of the test. This is an indication of excellent corrosion resistance, which is verified by SEM cross-sectioning and elemental EDS analysis. A brief explanation of the protective mechanism of the coating is provided.

Tubular asymmetric LSCF oxygen transport membranes (OTMs) were prepared on stainless steel substrates by PS-PVD and supersonic air-gas plasma spraying (SAPS). The microstructure of the thermally sprayed OTMs is examined by cross-sectional imaging and oxygen permeability is assessed via oxygen permeation flux measurements carried out at atmospheric pressure in an air-helium gradient. The findings from the cross-sectional analysis and oxygen permeation tests are reported and discussed.

In order to explore wear properties of Ni-based coating on the copper substrate, the coatings with different composition were designed. Ni-based coating, Ni-based/Al 2 O 3 and Ni-based/Al 2 O 3 /WC coatings were sprayed by HVAF on the copper substrates. Wear properties of different composite coating were measured at different loads at room temperature. The experimental results indicate that all the coatings have high wear resistance. Adding Al 2 O 3 in sprayed powders has little effect on the microstructures and wear properties of coating. The wear resistant is improved by the addition WC-12Co obviously. The best wear resistant is obtained when optimum WC-12Co content is added.

HVO/AF (High-Velocity-Oxygen/Air-Fuel) WC-17Co and WC-10Co4Cr coatings exhibit great potential in the replacement of electrolytic hard chrome (EHC) coating, and comprehensive properties of such coatings should be not worse than those of electrolytic hard chrome coating. The impingement-resistance of HVAF coatings sprayed on 300M ultra-high strength steel was studied in this paper. As an important property index, the fracture toughness of HVAF WC coatings was measured using micro-indentation method at the load of 9.8, 19.6, 24.5, 29.4 and 49.0N respectively. The cracks resulted from stress concentration in the micro-indentation were analyzed. The impingement-resistance for two HVAF WC coatings and EHC was evaluated according to the ASTM D3170 standard, and steel ball dropping experimentation was performed at the height of 0.61, 1.52, 1.83, 2.36 and 2.59m respectively. The cracks caused by both impingements were analyzed using SEM and optical microscopy in comparison with cracks in micro-indentation test.

The influence of the high velocity air fuel (HVAF) sprayed coating on the fatigue behavior of the low alloy steel was studied at different stress levels. It was observed that only one single main crack initiator existed in the substrate after fatigue at low stress levels, but there were multi-cracks on the substrate surface at high stress level. Detailed investigations showed that the cracks in the HVAF coatings sinuously extended to the interface and deflected thereat along the interface. Consequently, free-standing coating was formed due to its limited bond strength to the substrate and the lower elastic modulus than that of the substrate. The gap between the free-standing coating and the substrate surface was found to be correlated with the stress level. The high stress can greatly degrade the adhesion to the substrate causing the delamination of the coating. The cracks in the HVAF coating had no significant effect on the fatigue life of the substrate.

In this paper, the quality control in plasma spraying of chromium oxide ceramic coating on large area substrate is studied. This paper consists of three parts. Firstly, basic technical parameters are studied, for example, electric current, voltage, gas, powder, and spray distance. Secondly, the effect of dust from the spraying process on the coating quality is studied. Finally, the character of chromium oxide coating is researched. The results show that the dust from the spraying process greatly affects the coating quality. The effect of the following variables is examined: spray parameters, the powder size and distribution, and the substrate size. We have designed a set equipment to control the coating quality and the result was excellent. Now the equipment has been used in the production of anilox rollers and the patent has been applied. Meanwhile, we have devised a standard to determine the quality when spraying ceramic coating on large area substrate. The method has proved useful and efficient. Abstract only; no full-text paper available.

HVOF and plasma spray processes were used to apply Cr3C2-NiCr coatings, which were then characterized by X-ray diffraction and various other tests. The results revealed that the HVOF coatings were more stable than their plasma-sprayed counterparts as well as harder, tougher, less porous, and more erosion resistant. The HVOF coatings have been successfully used in industry and have proven to be an acceptable alternative to electroplated chromium.

A diameter of 30 mm polycrystalline diamond film has been deposited by magnet-enhanced DC plasma jet CVD. The diamond film was characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and surface profilograph. Results reveal that under the same depositing parameters, magnetic field can increase purity of diamond film, improve thickness uniformity of diamond film, but no influence on crystal perfection and size of microcrystal of diamond film. A discussion on magnetic effect is presented.