Moisture-proof and Enhanced Effect of Inorganic Coating on Porous Si_3N_4 Ceramic

Inorganic coating was fabricated on the surface of the porous Si3N4 ceramic by polymer derived（PD） and spraying technology, via using vinyl-polysilazane（PSN-1） as a preceramic polymer and Si3N4 and lithium aluminosilicate（LAS） powders as fillers. The phase and microstructure of the coatings were analyzed by X-ray diffraction（XRD） analysis and scanning electron microscopy（SEM）, respectively. The effect of the coatings on mechanical property and humidity resistance of the porous Si3N4 ceramic was investigated. The experimental results showed that we successfully fabricated the uniform and dense coating which preferably combined with the substrate upon the addition of fillers. The bending strength of the porous Si3N4 ceramic sprayed the coating increased by more than 18%, and the surface hardness increased by 1.7 times. The apparent porosity of the materials reduced by an average of 97.7%, and water absorption was below 0.5%. Therefore, the prepared coating with preferable density had an obviously moisture-proof and enhanced effect on the porous Si3N4 ceramic.

STUDY OF MIXED RARE EARTH METAL (REM) CONVERSIONCOATING ON ALUMINUM ALLOY LY12

The process of mixed rare earth metal (REM) conversion coating on aluminum alloy LY12 (2024) was introduced. The corrosion resistance of mixed REM conversion coating was examined by using weight loss test and electrochemical method. The results show that the mixed REM conversion coating increases the corrosion resistance of the alloy surface. Examination result of scanning electron microscope (SEM) shows that the coating exhibits honeycomb-like feature. X-ray diffraction (XRD) analysis reveals that the coating is amorphous. The result of X-ray photoelectron spectroscopy (XPS) indicates that mixed REM conversion coating consists predominantly of Ce and O. The contents of other rare earth elements (La, Pr) are relatively low.

Performance of polymer/CdS organic-inorganic hybrid LEDs

Organic-inorganic hybrid light emitting diodes(LEDs) were fabricated by incorporating cadmium sulphide(Cd S) nanoparticles in hole transporting layer and light emitting materials of a polymer LED. The Cd S nanoparticles with size of 10 nm were synthesized by precipitation technique. The LEDs incorporated with the Cd S nanoparticles show a reduction in turn on voltage and luminance. When the nanoparticles are incorporated in a suitable fluorene based light emitting polymer, the luminance is increased along with the decrease of turn on voltage.

Hydrophobic MAO/FSG coating based TENG for self-healable energy harvesting and self-powered cathodic protection

An organic/inorganic hybrid coating with self-healable hydrophobicity is prepared as triboelectrical layer by micro-arc oxidation(MAO)and fluorinated sol-gel(FSG)coating.The MAO/FSG hybrid coating-based TENG(MF-TENG)has a current output of31μA and voltage output of 870 V,which is eight times that of the MAO based TENG.Compared with organic coating,the organic/inorganic hybrid coating has good wear resistance.When the fluorine composition on the surface of the coating is damaged,the self-healing hydrophobicity and electrical output are achieved by transferring loaded perfluorosilane to the damaged surface.The fluorinated sol-gel coating is hydrophobic,which ensures that the coating has good corrosion resistance.Also,the electricity generated in triboelectrification could improve the anti-corrosion performance by cathodic protection.Based on the anti-corrosion,anti-wear and self-healing properties,the MF-TENG has potential applicability in the field of energy collection,energy supply,and corrosion protection.

Water vapor effects on the oxidation resistance of modified potassium silicate coating at high temperature

An inorganic potassium silicate coating with pigments of alumina,aluminum phosphate,NiCrAlY and copper chromite black was prepared on CB2 stainless steel.Oxidation behavior in either ambient air or O_(2)+H_(2) O mixture at 630℃ for 2000 h was comparatively studied,and the coating exhibited excellent resistance under both test conditions.The water vapor considerably accelerated the oxidation of the uncoated CB2 steel,as the hydroxide,the main constituent of the coating,had a negligible evaporation rate at test temperature,while it had a limited effect on the coated sample.Meanwhile,the existence of coating may prolong or eliminate the incubation period in the O_(2)+H_(2) O mixture at 630℃.After oxidation,the coating matrix is in an amorphous state and fillers as alumina and copper chromite black are stable in the coating.Leucite(KAlSi_(2) O_(6))formed by Al from NiCrAlY and potassium silicate in the coatings was detected after tests either in O_(2) or O_(2)+H_(2) O mixture.