Study On Low Temperature Preparation Of ZrSiO₄ Film Via Non-Hydrolytic Sol-Gel Method

Zirconium silicate(ZrSiO4)film was prepared at low temperature on silicon substrate with a(100)crystal plane orientation via nonhydrolytic sol-gel method by using zirconium tetrachloride(ZrCl4)as zirconium source,tetraethoxysilane(TEOS)as silicon source,ethanol as solvent,and lithium fluoride(LiF)as mineralizer.Effects of filtering process,solvent species,precursor concentration and heat treatment on the low-temperature synthesis of ZrSiO4 were studied by means of DTA-TG,XRD,FE-SEM and FTIR.Meanwhile,the influences of filtering process,solvent species,precursor concentration,drying temperature,calcination and coating processs parameters,such as pulling rate and coating times on the quality of film were also investigated.On this basis,surfactant was introduced to improve the stability of the sol and the wettability between sol and silicon substrate.The influence of surfactant species,surfactant adding times,surfactant addition amount and holding time on the quality of film were studied and the corrosion resistant property of film was investigated preliminary.The experimental results indicated that:ZrCl4 was filtrated and dissolved in ethanol with the precursor concentration of 0.7 mol L-1,followed by reflux at 110? for 24 h and being aged at room temperature for 24 h to get the zirconium silicate sol.The clean silicon substrate was pulled with the rate of 1.0 mm s-1,and then dryed at 50? for 2 h and calcined at 850? for 2 h to get a ZrSiO4 film.The dense and smooth ZrSiO4 film was achieved through two-stage thermal treatment:the product was slowly calcined at 500? with the rate of 1.0? min-1 to make the organic matter decompose completely,and then was heated to 850? for 0.5 h with the rate of 1.5? min-1 for complete crystallization with small grains.Increasing the heat treatment temperature over 850?,the grains was overgrowth,leading to the decrease of film density.Due to the strong hydrophobicity of polished silicon substrate,zirconium silicate sol was difficult to wet and coat.Therefore,the film area was restricted and multi-layer coating was limited.After introducing 3 wt%small molecule surfactant,tetrabutyl ammonium bromide(TBAB),the sol was stable owing to the electrostatic stabilization mechanism.Meanwhile,surface tension of the sol was decreased which made the sol wet the substrate easily and form a uniform adhesion layer.Thus,the film area increased,and the film had excellent corrosion resistance.The film was still complete after being corroded by 40%NaOH solution at 30? for 48 h.The preparation of ZrSiO4 film provides a new theory reference and research design for the preparation of other dense films.