Drying of Ceramics

Instructor:  Denis A. Brosnan, Ph.D., P.E.

Course description

Water is added to ceramic raw materials to activate plasticity and to achieve cohesion, thus allowing for forming the shape of the intended product. This water must be removed prior to the firing or sintering of the particulate mass. The water removal results in shrinkage of the formed part (ware), and the water must be removed at a sufficiently slow rate to prevent forming of cracks and other defects. The control of the drying rate involves the use of energy inputs and controlling evaporation at a rate that the parts can tolerate. The “tolerance” of ceramics is influenced by material characteristics, processing variables, and other factors that influence water and vapor migration rates from the internal areas of the formed part to the drying atmosphere. Fundamentally, ceramic dryers involve energy and mass transfer.

There are many types of dryers and the countercurrent airflow convection dryer is most frequently utilized with high production rates for ceramics. In technical and advanced ceramics of intricately shaped parts, microwave and radio frequency dryers are utilized. Other types of dryers are considered in the course to include spray dryers, airless dryers, and laboratory devices. All these dryers employ controls such that the maximum drying rate the parts can tolerate is not exceeded.

The control of dryers involves psychrometry of humid air mixtures, and “psychrometric charts” (sections of the water phase equilibrium diagram) are used. The charts allow for mixing of air volumes (such as heated air and ambient air) to be directed in the dryer, calculation of air volumes required for drying, and evaluation of dryer air utilization and thermal efficiency. Numerous examples are reviewed with students during the lectures.

For those involved in processing of ceramic products where drying is required, Drying of Ceramics explores the “why” and “how to control” elements of drying operations.

The course is divided into three units:

• Unit 1: Overview of Drying and Dryers
• Unit 2: Psychrometry and Dryer Control
• Unit 3: Dryers, Dryer Control, and Future Developments

Who will benefit?

Drying of Ceramics is intended for practitioners of all educational backgrounds with concepts presented in easily understandable terms. This includes:

• Manufacturing operators
• Production supervisors
• Managers, engineers, and scientists

What you'll learn

Students who complete the course will develop abilities to:

• Control dryers in processing of ceramics
• Understand and recognize sources of drying defects
• Gain insight into how processing prior to drying influences scrap rates
• Adjust dryers as required by changes in seasonal ambient weather and by changes in production rates (throughput)
• Reduce cost of fuels used in preparation of make-up air for drying
• Develop and maintain best practices in the laboratory (for those involved in product development)

Student resources

• The book, Introduction to Drying of Ceramics by Brosnan and Robinson is highly recommended for this recorded course. Homework will be assigned from this excellent reference book.
• Students are encouraged to obtain a psychrometric app such as “Psychrometric Chart” by Modern Psychrometrics (a free app that works on an iPhone or iPad). This app has a maximum air temperature of 200^oF/93^oC, and it can be used to illustrate use of the chart.

Customized training

Looking for training customized to your company? Do you want a course taught privately to your employees? Call Customer Service at 614-890-4700 for details, or contact Marcus Fish to learn about training benefits for our Corporate Partners.

For other questions about ACerS online courses, email customerservice@ceramics.org.