Common Defects in Injection Molding of Zirconia Ceramics

When zirconia ceramics are formed by injection molding, there are often some defects, such as pores, pinholes, cracks, mud strands, deformation, and other defects, so what are the causes of these defects? Now let us analyze the common defects in the injection molding of zirconia ceramics.

When zirconia ceramics are formed by injection molding, there are often some defects, such as pores, pinholes, cracks, mud strands, deformation, and other defects, so what are the causes of these defects? Now let us analyze the common defects in the injection molding of zirconia ceramics.

1.Stomata

The main causes of stomata:

• The moisture content of the mud is too little, the viscosity is too high, and the fluidity is poor, so that the bubbles in the mud are not easy to discharge.

• The mud is stored for too long, the mud temperature is too high, resulting in the mud fermentation; the mud is not stale.

• The type and dosage of electrolytes are inappropriate.

• The mud is stirred too violently, or the injection speed is too fast, so that the mud is sandwiched with air bubbles.

• There are impurities in the gypsum mold, such as sand or calcium carbonate, etc.; the particles of gypsum used in molding are too thick, so that the structure of the model is uneven; the surface of the model is stained with dust.

• The plaster mold is too dry, too wet, or the temperature is too high.

2.Crack

The main causes of cracking:

• the amount of plastic raw materials in the mud is improper, and the particles are too coarse.

• improper amount of electrolyte, or mud without stale, uneven mixing, and poor fluidity.

• the model varies from dry to wet, and the oil impurities on the surface are not removed before use.

• the injection operation is not good, and the residual slurry is not completely poured, resulting in uneven thickness and uneven drying shrinkage.

• the injection parts are released too early and too late, and the drying temperature is too high.

3.Deformation

The main causes of deformation:

• the mud is unevenly mixed, resulting in different drying shrinkage.

• too much moisture in the mud, resulting in large drying shrinkage.

• improper operation of the residual pulp and uneven thickness of the green body.

• if the model is too wet or molded too early, or if the mold is not operated properly, the wet billet is not flattened or straightened.

The above is the introduction of common defects in the injection molding of zirconia ceramics. Hope it can provide you with a reference.

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