Study On Improving The Corrosion Resistance Of Pollution-Free Ceramic Flux For On-glaze Pigments

Traditional pollution-free fluxes of alkali borosilicate(ABS)system for on-glaze pigments have disadvantages of low glossiness and poor corrosion resistance.In order to overcome these inherent drawbacks of traditional flux of ABS system,batch compositions of fluxes based on the ABS system were rationally designed and their performances were optimized with the purpose of improving the corrosion resistance of flux.And ultimately,fluxes with high glossiness and excellent corrosion resistance were prepared to improve the corrosion resistance of the ceramic decorative materials,especially alkali resistance.Firstly,the chemical corrosion mechanics of glass and ceramics were investigated in this research and the batch compositions of basic flux were formulated based on the result of orthogonal optimization of flux.Secondly,the influence of network intermediates on the performance of the resultant fluxes was interrogated through experiments of separate and combined addition of ZrO2 and TiO2.The effects of various amounts of rare earth oxides of Ta2O5,La2O5 and CeO2 were also investigated.Thirdly,on the basis of batch formula optimization,the optimized samples were heat treated and the influence of various duration times on the corrosion resistance and microstructure was studied.Properties and microstructure of samples were characterized by using glossmeter,XRD and TEM to analyze the relationships between composition,structure and properties of the fluxes.The chemical compositions of basic flux optimized through orthogonal test are as follows:SiO2 48.92wt%,B2O3 29.35wt%,A12O3 8.33wt%,Li2O2.17wt%,Na2O 2.66wt%,K2O 5.29wt%,CaO 3.28wt%.The as-prepared frit is of excellent fluidity and viscosity with uniform appearance and the glossiness is 77,alkali resistant degree is 42.8%,acid resistant degree is 94.8%.Results of the introduction of network intermediates of ZrO2 and TiO2 showed that corrosion resistance can be improved with the separate addition of 1.5wt%ZrO2 and 1.5wt%TiO2,respectively.The yellow hue resulted from the introduction of TiO2 can be alleviated and the transparency and fluidity of the flux can be improved on condition that the mass ratio of m(ZrO2)/m(TiO2)is 2,with which the glossiness and corrosion resistance after decoration firing can also be slightly improved.Results of the introduction of rare earth oxides showed that with the addition of 0.5wt%Ta2O5,0.5wt%La2O5 and 1.5wt%CeO2,respectively,the glossiness and corrosion resistance of flux are further improved.Comparisons between water quenched and heat treated samples of various oxides content with optimized compositions indicate that phase separation during heat treatment can effectively improve the glossiness and corrosion resistance of fluxes.Sample with addition 0.5wt%La2O5 and heat treated at 620? for 20h is of optimal properties with glossiness of 89.8 and alkali resistant degree of 69.8%.The purpose of improving the corrosion resistance of flux is achieved.The as-prepared flux was blended with on-glaze cobalt blue colorant to prepare so called over-glaze pigment.After decoration firing,the samples are of pure and bright coloration with excellent appearance and the colorimetric parameters experienced little variations before and after corrosion resistance tests.Thus ultimately,an effective avenue to improve the corrosion resistance of on-glaze pigments is explored.