In order to improve the ionic conductivity of lanthanum silicates, which have been considered as the new electrolyte candidates for intermediate temperature solid oxide fuel cells (IT-SOFCs), the feedstock powders are prepared by sintering the mixed oxide powders in different temperatures and sintering times. The main phase of all the samples is the hexagonal apatite structure. The apatite-type ceramic coatings with a typical composition of La 10 (SiO 4 ) 6 O 3 are deposited by atmospheric plasma spraying (APS). The influence of sintering time of feedstock powders on the electrical properties of La 10 (SiO 4 ) 6 O 3 electrolyte coatings is reported here. The highest conductivity of the dense composite electrolyte coatings reaches 6.8×10 -6 S·cm -1 at 435 °C in air which is comparable to other apatite-type lanthanum silicate (ATLS) conductors.

In this study, La 10 (SiO 4 ) 6 O 3 coatings deposited on aluminum substrates by atmospheric plasma spraying were investigated for potential for use as electrolyte layers in solid oxide fuel cells. By proper selection of spraying parameters, particularly the hydrogen gas flow rate, the La 10 (SiO 4 ) 6 O 3 ceramic layers showed good densification. The results suggest that atmospheric plasma spraying may be an appropriate method for the production of SOFCs.

Lanthanum silicate coatings were deposited onto stainless steel substrates by atmospheric plasma spraying (APS) using mechanically mixed (type A) and calcined feedstock (type B) powders. The phase composition, microstructure, density and porosity of coatings prepared from the two types of powder were compared.

In this paper, the effect of velocity on the characteristics of atmospheric plasma sprayed yttria stabilized zirconia was investigated through adjusting auxiliary helium flow. The temperature and velocity of in-flight particles were measured with DPV2000 analyzer. The results showed that helium flow significantly influenced particle velocity and less distinctly influenced particle temperature. The microstructure of the coatings was characterized by scanning electron microscopy and X-ray diffraction analyzer. The ionic conductivity of the deposits through thickness direction was measured by a potentiostat/galvanostat based on three-electrode assembly approach in a temperature range of 500-1000 °C. The specific gas permeability was estimated. The results showed that the gas permeability was improved by increasing the in-flight particle velocity. However, the in-flight particle velocity has little effect on the ionic conductivity of specimens.

The emergence of lanthanum silicate as an electrolyte is required to accelerate the development of synthesis techniques for intermediate temperature solid oxide fuel cells (ITSOFCs). Apatite-type oxide powders of La 10 (SiO 4 ) 6 O 3 have been elaborated through atmospheric plasma spraying (APS) using micro-scale mixtures of La 2 O 3 and SiO 2 powders. Granulometer and scanning electron microscopy analyses have indicated the result of high temperature reaction and rapid solidification in the evolution of multi-scale microstructure.

Ti(Al,O)/Al 2 O 3 based composite powders with three different compositions were produced by high energy milling, sintering and grounding. High velocity oxy-fuel (HVOF) spraying was used to coat these powders onto Ti-6Al-4V alloy samples. High temperature oxidation and hot corrosion behaviour of the coatings was studied in dry air and Na 2 SO 4 + NaCl vapour, respectively. The results showed that Ti(Al,O)/Al 2 O 3 coatings have a much improved oxidation and hot corrosion resistance compared to the substrate Ti-6Al-4V alloy. The oxide formed on the surface of the coatings after high temperature exposure is composed of a mixture of Al 2 O 3 and TiO 2 . The oxide scales have excellent adhesion to the coatings, showing superior scale spallation resistance. Microstructural analysis suggested that the Al 2 O 3 particles could act as a diffusion barrier to O and Ti therefore reducing the oxidation rate. The Al 2 O 3 phase also forms an interlocking network penetrating throughout the oxide scale, reinforcing the fragile TiO 2 containing scale. It is believed this composite system can provide a new generation of coatings to Ti based alloys, raising the application temperature of Ti alloys from ~650ºC to 800-900ºC without excessive scale spallation.