In addition to the thermal gelation benefits, METHOCEL™ increases the lubricity of the ceramic mix. Ceramic processing equipment, such as molds and dies, are susceptible to wear due to the friction that ceramic particles impart. By increasing lubricity, METHOCEL™ helps reduce particle wear to increase the service life of equipment and reduce energy costs associated with molding, casting, and extruding ceramic parts. Furthermore, METHOCEL™ burns out cleanly during firing, ensuring no residue is left that may impact the structural integrity or shape of the ceramic part.
Preventing Binder Migration
Many organic binders will migrate to the surface of drying ceramic bodies along with the evaporating liquid. This can cause a layer of binder to form at the ceramic surface, inhibiting drying. Upon firing, the migration and resultant uneven binder distribution can lead to stress cracks, surface blisters, and other surface defects. METHOCEL™ binders remain fixed in the three-dimensional network formed during thermal gelation and will not migrate to the surface. Therefore, ceramic bodies containing METHOCEL™ as a binder are more consistent and far less likely to show surface defects.
Gelation Variation of METHOCEL™ Binders
The thermal gelation temperature, gel firmness, and dynamic viscosity of a ceramic mix containing a METHOCEL™ additive vary based on the type and concentration of METHOCEL™ in the system. In particular, thermal gelation causes a significant increase in the apparent viscosity of ceramic mixes at varying concentrations and temperatures based on the grade used. This makes it easy to obtain the right balance of properties for each type of ceramic being manufactured.
Grade |
Concentration (wt %) |
Temperature (°C) |
Torque (meter-grams) |
METHOCEL™ A4M |
|
Start |
Peak |
Start |
Peak |
2.5 |
41 |
47 |
470 |
850 |
5.0 |
32 |
40 |
1180 |
1980 |
METHOCEL™ F4M |
2.5 |
48 |
55 |
390 |
540 |
5.0 |
43 |
52 |
800 |
1420 |
METHOCEL™ K15M |
2.5 |
64 |
68 |
350 |
420 |
5.0 |
52 |
63 |
760 |
1360 |
METHOCEL™ K4M |
2.5 |
78 |
82 |
50 |
150 |
5.0 |
60 |
72 |
620 |
850 |
How to Choose the Right METHOCEL™ Product
Apart from the considerations above, selecting the appropriate METHOCEL™ grade for a ceramic application depends on the formulation and processing requirements of processing techniques. The grades listed in the table below are starting point recommendations based on these techniques and applications.