Abstract An annealing separator for magnetic materials, such as oriented silicon steel and the like, consisting essentially of magnesium oxide and/or hydroxide with an addition of a decomposable phosphate compound. The phosphate addition, which may be in the form of an inorganic phosphate, may be added to the magnesium oxide and/or hydroxide in such amounts as to produce a P2O5 content on the order of 1-25 percent by weight of the total coating. Preferably, the P2O5 will be present in an amount of at least 1 percent, and up to about 15 percent. A magnetic material processed according to standard procedures and coated with said composition prior to a final high temperature anneal, will yield a product having an improved glass film.
The method claimed in claim 1 wherein said magnesium oxide and decomposable phosphate compound is applied as an aqueous mixture and dried in situ prior to said anneal.
Claim 2
Dependent Claim
28 words
The method claimed in claim 1, wherein said decomposable phosphate compound is present in such an amount as to yield from 1-15% P2O5, by weight, of the coating.
Claim 3
Dependent Claim
29 words
The method claimed in claim 1, wherein said decomposable phosphate compound is selected from the group consisting of phosphoric acid, calcium phosphate, aluminum phosphate, magnesium phosphate, and ammonium phosphate.
Claim 4
Dependent Claim
33 words
The method claimed in claim 4 wherein said decomposable phosphate compound is a calcium phosphate selected from the compounds whose chemical formulas are as follows: Ca(H2PO4)2, Ca (H2PO4)2.H2O, CaHPO4, and 3 Ca(PO2).Ca(OH)2 .
Claim 5
Dependent Claim
28 words
The method claimed in claim 4 wherein said decomposable phosphate compound is an aluminum phosphate selected from the compounds whose chemical formulas are as follows: A1PO4 and A1(PO3)3.
Claim 6
Dependent Claim
23 words
The method claimed in claim 1 wherein at least a portion of said decomposable phosphate compound is applied prior to said magnesium oxide.
Claim 7
Dependent Claim
14 words
The method claimed in claim 7 wherein said decomposable phosphate compound is phosphoric acid.