Slip casting is one of the oldest forming technology, the traditional grouting technique for single and double grouting, grouting pressure grouting and vacuum grouting etc. In recent years, the old slip casting technology has a series of new progress, there has been new slip casting technology such as centrifugal grouting, refrigerant grouting and tape casting. And it is gradually applied to the technology of cemented carbide alloy powder.

 

1, Centrifugal Grouting

When the slurry is injected into the mold, the mold is rotated at a certain speed, and the slurry is dehydrated to form a billet through the effect of centrifugal force. Under the action of centrifugal force, the bubble is concentrated in the central part of the slurry and eventually disappears because of the rupture.

 

 

Compared with the traditional grouting method, the thickness and density of the products are uniform, and the deformation is small. The preparation of raw material powder by centrifugal grouting must have a narrow particle size.

 

If the particle thickness is different, the coarse particles will be more concentrated by centrifugal force and concentrated on the inner surface of the body, while the fine particles will be concentrated on the outer surface of the green body and form a gradient.

 

The inhomogeneity can cause inhomogeneous shrinkage and segregation of components during drying or sintering, thus affecting material properties. As the tungsten carbide has a variety of particles, the size and density of the composition are not uniform. If this method is adopted, the composition of the mixture is strictly controlled.

 

2, Refrigerant Grouting

Refrigerant grouting is the solidification of slurry in mold when the slurry is solidified, and a certain shape of the bad body is obtained. Then, the drying medium is obtained by freeze drying. Based on the principle that there is no capillary collapse in ice sublimation, this method can avoid the close and contraction between fine powders in the billet, so as to effectively eliminate the segregation of particles and components caused by settlement, and prepare materials with uniform porosity. 

 

Compared with the traditional casting method, it can reduce organic additives content and shorten the skim cycle. Meanwhile, it eliminates the subsequent drying process, avoids drying shrinkage and does not produce shrinkage stress

 

3, Tape Casting

Pouring slip casting in specific substrate is the tape casting. It mainly used for the preparation of products of thickness changes between 5µm to few millimeters and it is particularly suitable for the preparation of multi-layer composite material.