Study On Particle Dispersion Prestressing Strengthening Domestic Ceramics

Porcelain products have been widely used for traditional applications owing to their wear resistance,corrosion resistance,and good thermal stability.However,porcelain has obvious disadvantages such as a low deformation energy and sensitivity to defects,which limit its use in additional fields.The theoretical strength of porcelain products is relatively high,but in practical application,their fracture strength is quite different from the theoretical value.In order to solve this problem,many researchers have carried out research on the reinforcement of ceramic materials,but compared with the concrete and glass materials reinforced by pre-stress,the current research still has a large gap.Prestress refers to the introduction of stress in the material in advance to resist the external failure load,thus increasing the strain required for material cracking,improving the fracture strength and reliability of the material.The strength of concrete can be increased by 2-3 times and the strength of glass can be increased by 4-5 times.In contrast,prestressed reinforced ceramic materials are still in the research and exploration stage.This paper proposes a new design of prestressing porcelain,i.e.forming prestressing inside the billet to strengthen porcelain,i.e.using porcelains as the matrix and introducing different kinds of reinforcing phases into it to strengthen porcelains with internal prestressing.The main research results are as follows:（1）Using the K₂O-Al₂O₃-SiO₂ ternary phase diagram as a guide,the formulation of porcelains was designed by selecting suitable ingredient points and the porcelain blanks were home-made.By changing the size of quartz particles in the base formulation and observing the change in strength of the porcelains after firing,the optimum quartz particle size was determined;by introducing different contents of quartz into the base formulation,the effects of firing temperature,holding time and quartz addition on the bending strength of the porcelains were investigated,and the changes in mechanical properties and microstructure of the porcelains were analyzed.The results show that the change of quartz particle size would affect the final bending strength of the porcelain,and too large or too small particle size reduced the strength of the porcelain.The added quartz also dispersed inside the porcelain and affect the strength of the porcelain.When the sintering temperature was 1280℃,the holding time was 30 minutes,and 15 wt.%quartz was added,the porcelain reached the highest strength.Compared with the samples without additional addition,the bending strength increased from（55±9）MPa to（94±8）MPa,with the growth rate reaching 71%,and the fracture toughness increased by 23%.（2）The types of reinforcing phase were changed,and two different types of ZrO₂（pure ZrO₂ and Y₂O₃ stabilized ZrO₂）were introduced into the basic formula.This study investigated the effects of the amount of ZrO₂,the firing temperature,and the holding time on the porcelain phases,microstructure,bending strengths and fracture toughness values,and compared the reinforcing effects of two types of ZrO₂.The results show that the effect of the two types of ZrO₂（pure ZrO₂ and Y₂O₃-stabilized ZrO₂）on porcelain reinforcement were similar and that the optimal porcelain reinforcement was obtained with a ZrO₂ content of 6 wt.%,firing temperature of 1320℃,and holding time of 30 min.The bending strength increased to（89±8）MPa（pure ZrO₂）and（87±8）MPa（Y₂O₃-stabilized ZrO₂）.The two types of ZrO₂ have similar reinforcing effect on porcelains,but the toughening effect of pure ZrO₂ is better because of the phase transformation in porcelains.（3）ZrSiO₄ is also one of the important raw materials in the ceramic industry.In this part,the influence of ZrSiO₄ content on the sintering performance,mechanical properties,phase and microstructure of porcelains was studied,and its strengthening mechanism was analyzed.The results show that due to the difference of thermal expansion coefficient between zirconium silicate particles and matrix,residual stress was generated in the matrix,resulting in increased the porcelain strength.The optimum sintering temperature was1300℃,and the optimum holding time was 30 min.Under this condition,when adding 6wt.%ZrSiO₄,the porcelain strengthening effect was the best,reaching（106±11）MPa,with an increase of 83%.