High strength feldspathic porcelain and method for producing the same

Claim 1

High strength feldspathic porcelain with an unglazed bending strength of more than 1,400 kg/cm 2 , the porcelain consisting essentially of 22-85% by weight of Si0 2 , 10-73% by weight of Aℓ 2 O 3 , and 1.5-6.5% by weight of at least one oxide selected from the group consisting of K 2 0 and Na 2 0; the porcelain having a crystal phase formed of at least one kind crystals selected from the group consisting of corundum, mullite, cristobalite, and quartz, a total degree of crystallinity of said crystal phase being more than 40% by weight, degree of crystallization for said crystals being selected in ranges of not greater than 60% by weight for corundum, 5-50% by weight for mullite, not greater than 40% by weight for cristobalite, and not greater than 10% by weight for quartz, grain size of said crystals being not greater than 20 µm, and said porcelain being free from defects larger than 40 µm.

Claim 7

A method for producing high strength feldspathic porcelain having an unglazed bending strength of more than 1,400 kg/cm 2 and being free from defects larger than 40 µm, comprising steps of preparing a starting material selected from the group consisting of quartz type material, feldspathic material, and alumina type material; pulverizing the starting material so as to make 85-95% by weight thereof into particles with effective diameters not greater than 10 pm; calcining the pulverizing material at 900-1,400°C; mixing clay-mineral material with the calcined material; pulverizing mixture thus produced so as to make not greater than 85% by weight thereof into particles with effective diameters not greater than 10 µm; forming and drying the pulverized mixture; and firing the formed and dried mixture at 1,000-1,400°C, whereby said porcelain thus produced contains a crystal phase formed of at least one kind crystals selected from the group consisting of corundum, mullite, cristobalite, and quartz, said crystal phase having a grain size of not greater than 20 µm and a total degree of crystallinity of more than 40% by weight.

Claim 8

A method for producing high strength feldspathic porcelain having an unglazed bending strength of more than 1,400 kg/cm 2 and being free from defects larger than 40 µm, comprising steps of preparing a starting material selected from the group consisting of quartz type material, feldspathic material, and alumina type material; pulverizing the starting material so as to make 85-95% by weight thereof into particles with effective diameters not greater than 10 pm; calcining the pulverizing material at 900-1,400°C; mixing clay-mineral material with the calcined material; pulverizing mixture thus produced so as to make not greater than 85% by weight thereof into particles with effective diameters not greater than 10 µm; forming and drying the pulverized mixture; and firing the formed and dried mixture at 1,000-1,400°C, whereby said porcelain thus produced contains a crystal phase formed of at least one kind crystals selected from the group consisting of corundum, mullite, cristobalite, and quartz, said crystal phase having a grain size of not greater than 20 µm and a total degree of crystallinity of more than 40% by weight.

Claim 13

A method for producing high strength feldspathic porcelain having an unglazed bending strength of more than 1,400 kg/cm 2 and being free from defects larger than 40 µm, comprising steps of preparing a starting material selected from the group consisting of quartz type material, feldspathic material, and alumina type material; pulverizing the starting material so as to make 85-95% by weight thereof into particles with effective diameters not greater than 10 µm; calcining the pulverizing material at 900-1,400°C; pulverizing the calcined material: mixing clay-mineral material with the calcined material so as to make not greater than 85% by weight thereof into particles with effective diameters not greater than 10 pm; forming and drying the pulverized mixture; and firing the formed and dried mixture at 1,000-1,400°C, whereby said porcelain thus produced contains a crystal phase formed of at least one kind crystals selected from the group consisting of corundum, mullite, cristobalite, and quartz, said crystal phase having a grain size of not greater than 20 µm and a total degree of crystallinity of more than 40% by weight.

Claim 14

A method for producing high strength feldspathic porcelain having an unglazed bending strength of more than 1,400 kg/cm 2 and being free from defects larger than 40 µm, comprising steps of preparing a starting material selected from the group consisting of quartz type material, feldspathic material, and alumina type material; pulverizing the starting material so as to make 85-95% by weight thereof into particles with effective diameters not greater than 10 µm; calcining the pulverizing material at 900-1,400°C; pulverizing the calcined material: mixing clay-mineral material with the calcined material so as to make not greater than 85% by weight thereof into particles with effective diameters not greater than 10 pm; forming and drying the pulverized mixture; and firing the formed and dried mixture at 1,000-1,400°C, whereby said porcelain thus produced contains a crystal phase formed of at least one kind crystals selected from the group consisting of corundum, mullite, cristobalite, and quartz, said crystal phase having a grain size of not greater than 20 µm and a total degree of crystallinity of more than 40% by weight.