Study on the Microstructure of Anti-Corrosion and Wear Resistant Coating on the Inner Wall of Equipment Pipeline and the Synthesis Mechanism of Ceramic Coating

A corrosion-resistant and wear-resistant coating was prepared on the inner wall of copper tube by centrifugal self-propagating melting. The surface morphology, composition and phase composition of the ceramic lining FGM coating were analyzed by XRD and SEM, and the synthesis mechanism of the ceramic coating was studied. The results show that the functionally gradient coating is composed of three layers: ceramic inner layer, metal transition layer and copper substrate layer. The surface of ceramic lining is smooth and dense, which is mainly composed of Al2O3, CaF2 and a small amount of Fe Al spinel. The results show that the alumina phase is dendrite like and grows outward perpendicular to the tube wall, and the low melting point phase is evenly distributed in the dendrite gap, which effectively improves the density of the ceramic layer.

Study on the Microstructure of Lining-Ceramic Layer

Aiming at phenomenon of serious friction and wear in industrial products,a new technology using the redundant heat of molten steel to prepare lining ceramic layer on the surface of casting steel was researched. The abrasion resistance was improved significantly because the interface between ceramic particles and the matrix metal combine in metallurgy way. The ceramic compound powder was granulated and sintered on the surface of the casting steel. Ceramic lining layer with high abrasion resistance formed rely on superfluous heat from molten steel. The microstructure of the lining ceramic layer was analyzed with SEM. The results show that the ceramic phase distributes equably in the lining ceramic layer and combines strongly with the matrix, so can boost wear resistance effectively.

On the Performance of Porous Sound Absorbent Ceramic Lining in a Combustion Chamber Test Rig

This paper discusses the potential of using porous ceramic lining as insulating material in combustion chambers with respect to their sound absorbent ability to suppress thermoacoustic instabilities. For this purpose a combustion chamber test rig was developed and different types of ceramic linings were tested. The examined range of power was between 40 and 250 kW and the air-propane equivalence ratio was between 1.2 and 2.0. The overall sound pressure level and frequency domain of a lean premixed swirl stabilized and piloted burner are presented. The resonance frequencies and sound pressure levels are obtained and compared for the different combustion chamber linings. The results show a significant decrease in overall sound pressure level by up to 23.5 dB for sound absorbent lining in comparison to the common sound reflecting combustion chamber lining. In summary, sound absorbent ceramic combustion chamber lining can contribute to improve the stability of lean premixed gas turbines.

Probabilistic finite element analysis of residual stress formation in shrink-fit ceramic/steel gun barrels

The development of residual stresses in a hybrid α-SiC lining/CrMoV steel jacket gun barrel during shrink fitting of the jacket over the lining is studied using a probabilistic finite element analysis. Particular attention is given to understanding the development of the axial compressive stress in the ceramic lining, since this stress (if sufficiently high) can prevent lining failure caused by formation and growth of circumferential cracks near the barrel ends. To quantify the effect of variability in various design, material and process parameters on the magnitude and the distribution of the axial residual stress, a probabilistic structural analysis approach, known as the advanced mean value (AMV) method, is used, enabling determination of the cumulative distribution function for failure of the lining. The results obtained are validated using the adaptive importance sampling (AIS) method, an efficient direct statistical sampling technique. Lastly, the corresponding sensitivity factors which quantify the effect of variability in each parameter on the magnitude of axial residual stresses in the ceramic lining are computed. The results indicate that the loss of the compressive axial stress in the lining near the barrel ends is affected to the greatest extent by the magnitude of the friction coefficient at the lining/barrel interface.

Time-Dependent Reliability of Ceramic Components Subjected to High-Temperature Loading in a Corrosive Environment

The time-dependent reliability of ceramic components subjected to high temperature loading can be analysed using multiaxial Weibull theory and its generalisations. In this approach it is assumed that no additional flaws are initiated during exposure to high temperatures. However, this may not be true in a highly corrosive environment such as in a combustion chamber. Additional flaws can be generated by surface oxidation, volume damage or by formation of circular pits on the surface of the component. These cases are considered in this paper. The relations for the failure probabilities are derived starting from classical Weibull theory. A fastener bolt for the ceramic lining of a combustion chamber is considered as an example.