Electrical porcelain troubleshooting
Eliminate porcelain defects with the support of our experts
If your products suffer from shaping defects, drying defects, firing defects or poor vitrification, let our experts help find the cause – and the solution.
During the production of large electrical porcelain specimens the shaping, drying and green handling stages are extremely sensitive. Serious defects can occur if the body is not sufficiently strong, plastic or has poor drying properties. For example, cracks may appear that require reprocessing work or the piece may not be recoverable at all.
The key to achieving good shaping properties is to use clays with a high level of workability or plasticity. So we developed a test to assess the workability of clays and bodies. The test characterizes the amount of work energy that can be applied to a clay (or full-body formulation) without causing the clay to crack. This indicates either how hard a clay (or body) can be worked, or how likely it is to crack under given conditions. High workability can also control the formation of cracks during drying.
Imerys’ portfolio contains a range of products, with good to high levels of workability, that can improve the shaping characteristics of your ceramics bodies – allowing faster production or higher yields.
- UK: Hymod Blue
- US: M & D
- Thailand: Thaiplas BC2
- India: PowerClay ND10
Using clays with a good mineralogy in terms of drying shrinkage can help reduce the build-up of drying stresses during the drying process – allowing faster drying and reduced drying cracks.
The balance of workability and drying performance is key in the use of clays for electrical porcelain production. A clay with high workability may still lead to drying cracks if the workability comes from minerals with poor drying characteristics.
We offer a range of products with mineralogies that provide a good balance of workability and drying performance allowing faster production and higher yields.
- UK: Hymod Blue
- US: M & D
- Thailand: Thaiplas BC2
- India: PowerClay ND10
Electrical porcelain specimens are often very large. This makes their firing difficult and sensitive to several potential defects. Large electrical porcelain specimens must be fired very carefully in order to allow all gasses generated during firing to be released so as to prevent large firing defects such as blue or black coring. For this reason, it is important to use clays with low amounts of gas-forming materials – for example, low carbon. This allows specimens to be fired faster and with fewer blue or black core defects.
We have a range of low-carbon products allowing faster production and higher yields. Ask our team which is the right one for you.
- UK: Hymod Blue
- US: M & D
- Thailand: Thaiplas BC2
- India: PowerClay ND10
Electrical porcelain insulators require high fired strength in order to resist the stresses to which they will be subjected during their lifetime. It’s important to use clays with low silica content in order to maximize fired strength – and minimize the amount of alumina that may have to be added to the body to compensate.
We offer a range of products designed to have as low silica as possible, perfectly suited to improve low fired strength.
- UK: Hymod Blue
- US: M & D
- Thailand: Thaiplas BC2
- India: PowerClay ND10
It is important for electrical porcelain to have a very homogeneous fired structure. This is because microscopic variations in the structure of the fired porcelain can lead to low fired strength or poor dielectric characteristics.
It’s important to use clays with good alkali levels (feldspathic materials) otherwise they may be refractory and prevent good vitrification. Clays with good levels of alkali can help reduce firing times/temperatures as well as problems associated with these microscopic defects.
Finally, poor vitrification can also lead to weathering and crazing problems for electrical porcelain over time. We offer a range of products designed to have a good level of mainly potassic bearing feldspathic material.
- UK: Hymod Blue
- US: M & D
- Thailand: Thaiplas BC2
- India: PowerClay ND10
Talk to our knowledgeable and experienced ceramics team about how our minerals can aid your processes, with these challenges and many others.
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