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Glass-bonded Crystalline Minerals and a Method of Production.

Ivey-KH; Chastain-SJ; Shell-HR
U S Pat 3 516 810 1970 Jun; :
A glass-bonded crystalline mineral is prepared from a synthetic mineral selected from mica, amphiboles, humites, spinel, zirconia, norbergite, and titania and glass compositions free of b. For example, the raw materials for producing fluor-phlogopite were weighed as mgo 28.7, Al2o3 7.44, Sio2 19, k2sif6 19.33, and feldspar 25.53 pct. The raw materials for the glass-forming composition were weighed as pbo 55, al2o3 9.3, and sio2 35.7 pct. The combined raw materials were mixed for 30 min in a 50:50 ratio. A pressure of 2 tons/sq in was used to cold press the mixture into preforms, which were placed in a kiln, heated to 1,100 deg c, and maintained at this temperature for 1 h. During heating, at 800 deg c the material was dry, the glass components formed a glass, and initial crystal development occurred. At 800 deg-1,000 deg c, crystals of synthetic mineral reached 1-2 micrometers in size and were increasing. At 1,000 deg-1,100 deg c, fluor-phlogopite, mica, lead mica, fibrous humite, minute spinel particles, and crystalline norbergite continued to grow. At 1,100 deg c the crystal size increased to 3-5 micrometers during a 1-h soak. The preform was rapidly cooled to 880 deg c, molded at a pressure of 2-5 tons/sq in for 1-3 min in a mold heated to 625 deg c, then cooled in an annealing furnace from 625 deg c to room temperature in 12 h. The product was impervius with increased impact strength; dielectric constant 7.55, Dissipation factor (ASTM) 0.0013, Loss factor (ASTM) 0.0098, Flexural strength 17,000 psi, and density 3.65.
Publication Date
Document Type
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
PAT 3,516,810
NIOSH Division
Source Name
U.S. Pat. 3,516,810; June 23, 1970; Chem. Abstr. 73:80,149A