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CERAMIC INJECTION MOULDING

Ceramic Injection Moulding (CIM) is an innovative forming technique to manufacture ceramic components with a high geometric complexity, narrow dimensional tolerances and sharp edges. In most cases, machine finishing is not necessary, even when the smoothest of surfaces are required.

In this technology, the molten feedstock is forced into a mould cavity by an injection moulding machine similar to that used in conventional plastic moulding. Because mould constructions also are often the same as those typically used in plastic injection, it is easy to design new products and applications.

An injection material is a homogeneous pelletised feedstock, containing ceramic powders compounded with thermoplastic binders. The binders in a temperature of 150 - 170° C form a liquid medium which carries the ceramic powders into the mould during the injection stage. In INCERAMICS Sp. z o.o. we can use CIM with nearly all ceramic materials, typically using high alumina and structural zirconia ceramics, in addition to zirconia solid electrolytes. After forming the part, we can remove in water bath approximately 50% of the plastifier from our products. Then a component goes through two thermal processes: first is pyrolysis in 300° C to remove the rest of binder, and a second - sintering in a high temperature 1300 - 1700° C.

With good process control close tolerances can be obtained, therefore machining of the part after sintering is usually not necessary. We can keep dimensions of final products in a tolerance +- 0,03 mm and the thickness of walls in +- 0,01 mm.

Maximal width of walls in our technology is 15 mm - with no risk of deformation during sintering.

It is possible, on every stage of manufacturing, to use machining processes like turning, milling or grinding.

Ceramic materials most frequently used in INCERAMICS S.A:

1) Alumina Al₂O₃ - high degree of scratch and thermal resistance, as well as hardness:

Flexural strength: 300 - 380 MPa

Compressive strength: 2600 MPa

Maximal usable temperature: 1750° C

2) Yttria Partially Stabilized Zirconia ZrO₂-Y₂O₃ - highly durable, high flexural strength, as wells as good slide characteristics:

Flexural strength: up to 1000 MPa

Compressive strength: up to 4500 Mpa

Maximal usable temperature: 1500° C

3) Yttria Fully Stabilized Zirconia ZrO₂-Y₂O₃ - possesses selective ionic conductivity and excellent thermal resistance:

Flexural strength: 200 MPa

Compressive strength: 2000 MPa

Maximal usable temperature: 2200° C

4) Zirconia - Alumina composite possessing unique thermomechanical properties, including high thermal shock resistance, mechanical strength and hardness.

Mechanical, thermal and electrical properties
of selected ceramic materials

Mechanical	Unit	Al₂O₃ 94%	Al₂O₃ 96%	Al₂O₃ 99,5%	ZrO₂, Y₂O₃ partially stabilised
Density	g/cc	3,69	3,72	3,89	6
Porosity	%	0	0	0	0
Color	-	white	white	ivory	ivory
Flexural Strength	MPa	330	345	379	900
Elastic Modulus	GPa	300	300	375	200 - 270
Shear Modulus	GPa	124	124	152	85
Bulk Modulus	GPa	165	172	228	-
Poisson's Ratio	-	0,21	0,21	0,22	0,23
Compressive Strength	MPa	2100	2100	2600	3900
Hardness	kg/mm²	1175	1100	1440	1300
Fracture Toughness	MPa	3,5	3,5	4	13
Maximum Use Temperature	°C	1700	1700	1750	1500
Thermal
Thermal Conductivity	W/m*°K	18	25	35	2
Coefficient of Thermal Expansion	10^-6/°K	8,1	8,2	8,4	10,3
Specific Heat	J/kg*°K	880	880	880	400
Electrical
Dielectric Strength	ac-kv/mm	16,7	14,6	16,9	9
Dielectric Constant	@1MHz	9,1	9,0	9,8	29
Dissipation Factor	@1kHz	0,0007	0,0011	0,0002	-
Volume Resistivity in 20°C	ohm*cm	>10¹⁴	>10¹⁴	>10¹⁴	>10¹⁰

You can download this table in the Acrobat Reader file here.

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