Abstract

Ceramic thin plates are applied to several industrial purposes including electronic materials and sensors. Drying-induced shrinkage and strain-stress formation of a ceramic thin plate were studied experimentally and theoretically. A kaolin thin plate molded into 10 mm × 30 mm × 1 mm was dried in a hot air stream, and the drying characteristics and deformation were examined. Modeling was also performed to predict the behavior. Heat and moisture transfer conservation equations and constitution equations based on viscoelastic strain-stress were simultaneously solved by a finite element method. A test piece of the thin plate was warped when only one side of the plate was dried, while it was almost flat when both sides were dried. The behaviors of drying and deformation were predicted with a reasonable agreement by the modeling. Parametric analyses by the modeling revealed that the drying conditions with faster drying rate in the beginning period resulted in formation of greater maximum principal stress, and drying on only one side of the plate induced stronger tensile stress in falling rate period than that with both sides drying. The larger thickness of the plate influenced the formation of significantly greater tensile stress but affected maximum compressive stress only a little.

Highlights

  • In drying processes of ceramics, molded wet clay is subjected to internal strain-stress formation induced by shrinkage

  • This deviation of the moisture content may have been caused because the convective heat transfer coefficient was greater than that used in the modeling or heating, and evaporation did take place on the top surface of the plate and became a little significant partly on the bottom surface of the plate in the one side drying experiment by hot air at 120 ◦C due to deformation warping the thin plate sample plate upward, as specified later

  • Hot-air drying of ceramic thin plates was studied to investigate the transient behaviors of drying-induced strain-stress and deformation

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Summary

Introduction

In drying processes of ceramics, molded wet clay is subjected to internal strain-stress formation induced by shrinkage. Ntinuous steady state operation, but a specified narrow part of the sheet can be supposed to be equivalent to the fact that drying proceeds transiently if the thermal conduction and moisture diffusion are ignored in the direction along movement of the sheet and the edge effect of the sample is negligibly small due to thin thickness in the order of 1 mm The s3a0.m0 ple hold30e.r0 was connected tIonittihalesaemlepclterowneigchbt a[gla] nce to measur0e.6t2h2e trans0ie.2n9t5 behavi0o.6r7o3 f the s0a.m64p0le weig0h.6t6.7The

Modeling
Heat and Moisture Transfer
Strain-Stress Analysis
Physical Properties and Parameters for Simulation
Transient Moisture Content and Temperature
Profiles of Moisture Content and Temperature
Drying-Induced Stress Formation
Effect of Plate Thickness on Drying-Induced Stress
Conclusions

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