Williams Advanced Materials Inc. of Buffalo, N.Y., has purchased Cerac Inc. The acquired company will operate as a wholly owned subsidiary and continue to manufacture specialty inorganic chemicals and thin-film materials under the Cerac name at its facility in Milwaukee, where its work force will remain in place.

The companies have worked in a customer-supplier relationship for many years. The New York firm is a subsidiary of publicly held Brush Engineered Materials Inc. in Cleveland.