Abstract: A glass funnel suitable for a chemical strengthening method of an electric field application type without impairing the safety of a cathode ray tube. A glass funnel for a cathode ray tube, characterized in that glass at a body portion 3 contains at least Na2O and K2O, the conductivity of said glass at the strain point is at least 4×10?6 S/cm, the conductivity at 150° C. is at most 5×10?12 S/cm, and a compressive stress layer is formed by a chemical strengthening method on at least part of the outer surface of the body portion 3.

Abstract: The present invention is to obtain a glass bulb of reduced weight, and high safeness and reliability by ion exchanging which assures a compressive stress layer having an effective thickness even to a large tensile vacuum stress. For this purpose, a region in an outer surface of a body portion 4 of the glass funnel, the region having a small mechanical strength and producing the maximum tensile vacuum stress thereby causing breakage easily, is partly strengthened by ion exchanging method according to an electric field assisting method and an ion exchanging method using paste in combination, whereby a portion 9 strengthened by ion exchanging method is provided in that region wherein the concentration of doped ions in a strengthened compressive stress layer is distributed according to a substantially step function in a direction from the surface of the glass toward the inside of it.

Abstract: A glass funnel suitable for a chemical strengthening method of an electric field application type without impairing the safety of a cathode ray tube. A glass funnel for a cathode ray tube, characterized in that glass at a body portion 3 contains at least Na2O and K2O, the conductivity of said glass at the strain point is at least 4×10?6 S/cm, the conductivity at 150° C. is at most 5×10?12 S/cm, and a compressive stress layer is formed by a chemical strengthening method on at least part of the outer surface of the body portion 3.

Abstract: A glass funnel for a cathode ray tube, which has a substantially rectangular opened end at one end and a neck portion at the other end and which constitutes, together with a glass panel having a substantially rectangular face portion, a glass bulb to be used for a cathode ray tube, wherein the glass constituting the glass funnel contains, by molar percentage, at least 60% of SiO2 and at least 7% of PbO; when the molar percentages of Na2O and K2O contained in said glass are represented by WNa and WK, respectively, 0.35?WK/(WNa+WK)?0.6; a compressive stress layer is formed by chemical tempering at least in the outer surface of a region containing a position where the tensile stress formed when the interior of the glass bulb is vacuumed to produce the cathode ray tube, becomes maximum; and either one or both of the outer surface of the chemically tempered region and the inner surface opposite to said outer surface, are colored by ion exchange coloration.

Abstract: There is provided a glass funnel for a cathode ray tube, which has a deflection angle of 120 deg or more, which has a concave portion in a funnel body portion around a yoke portion so as to have a depth of 10 mm or more, wherein a compressive stress layer is formed in a position where a tensile stress, which is generated on an outer surface of the funnel body portion, takes a maximum value &sgr;VTmax, the compressive stress layer has a compressive stress value &sgr;C of 80 to 350 MPa, the compressive stress layer has a thickness of 60 &mgr;m or more, and the maximum value &sgr;VTmax is 10 to 100 MPa.

Abstract: A glass funnel for a cathode ray tube, which has a substantially rectangular opened end at one end and a neck portion at the other end and which constitutes, together with a glass panel having a substantially rectangular face portion, a glass bulb to be used for a cathode ray tube, wherein the glass constituting the glass funnel contains, by molar percentage, at least 60% of SiO2 and at least 7% of PbO; when the molar percentages of Na2O and K2O contained in said glass are represented by WNa and WK, respectively, 0.35≦WK/(WNa+WK)≦0.6; a compressive stress layer is formed by chemical tempering at least in the outer surface of a region containing a position where the tensile stress formed when the interior of the glass bulb is vacuumed to produce the cathode ray tube, becomes maximum; and either one or both of the outer surface of the chemically tempered region and the inner surface opposite to said outer surface, are colored by ion exchange coloration.

Abstract: The present invention is to obtain a glass bulb of reduced weight, and high safeness and reliability by ion exchanging which assures a compressive stress layer having an effective thickness even to a large tensile vacuum stress. For this purpose, a region in an outer surface of a body portion 4 of the glass funnel, the region having a small mechanical strength and producing the maximum tensile vacuum stress thereby causing breakage easily, is partly strengthened by ion exchanging method according to an electric field assisting method and an ion exchanging method using paste in combination, whereby a portion 9 strengthened by ion exchanging method is provided in that region wherein the concentration of doped ions in a strengthened compressive stress layer is distributed according to a substantially step function in a direction from the surface of the glass toward the inside of it.

Abstract: An aluminum nitride sintered product which is made mainly of aluminum nitride and contains an yttrium compound in an amount of from 0.6 to 5 wt % as calculated as yttrium oxide, a vanadium compound in an amount of from 0.02 to 0.4 wt % as calculated as vanadium and carbon in an amount of from 0.03 to 0.10 wt % and which has a three-point bending strength of at least 45 kg/mm and a thermal conductivity of at least 150 W/m·K, wherein crystal grains of aluminum nitride have an average grain size of at most 5 &mgr;m.

Abstract: A basic structure of a screw joint coupling for oil pipes according to the invention is that a main sealing portion is constructed with a sealing portion formed axially in convex at an end of a male screw, and with a sealing portion formed in taper at an inner side of a female screw, and that the male screw and the female screw are butted at an end point of the former and an end part of a stopper formed at an inner side of the latter. The main sealing portion has a shrinkage allowance .DELTA.D of the seal part, which is regulated in size in a relation between a shrinkage allowance .DELTA.d of the screw and a pressure P of the sealing part. In addition, specific values are selected as to the load flank angle, the radius of curvature in convex of the sealing portion of the male screw, and the tapering angle of the sealing portion of the female screw.