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US 3,960,995 AGranted
Method for prestressing a body of ceramic material
OwnerJacques P. Kourkeneinventor
Life of this patent
Estimating the term…
Abstract
Thermal prestressing methods using unit and selective heating of tendons incorporated in a ceramic or cermet body to selectively elongate the tendon with respect to the body and soften the latter. Upon cooling an anchorage bond is formed between the body and the ends of the tendons, which bond develops a tension in the tendon and prestress in the body upon further cooling. Bodies are also prestressed by forming a bond between the tendon and the body and then heating the body in use so as to elongate the tendon relative to the body, the tendon having a greater coefficient of expansion than the material of the body.
Claims33
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body, said tendon having a greater coefficient of linear thermal expansion than the material of said body,
- b. elevating the temperature of said tendon and the region of said body immediately surrounding said tendon to at least the softening temperature of the material of the body so that said tendon elongates and undergoes differential thermal expansion with respect to said body,
- c. lowering the temperature of said tendon and the region of said body immediately surrounding said tendon so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said region to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to said body as a result of its greater coefficient of linear thermal expansion as respects said body, said bond stress anchorage developing the entire tensile force in said tendon.
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body, said tendon and said body each having a positive coefficient of linear thermal expansion, the coefficient of linear thermal expansion of said body being greater than that of said tendon,
- b. elevating the temperature of said tendon and region of said body immediately surrounding said tendon to at least the softening temperature of the material of the body so that said tendon elongates and undergoes differential thermal expansion with respect to unsoftened portions of said body,
- c. lowering the temperature of said tendon and the region of said body immediately surrounding said tendon so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said region to thereby generate a bond stress anchorage between said tendon and said unsoftened portions of the body to prestress said ceramic body, said tendon seeking to contract with respect to said unsoftened portions of the body as a result of its linear thermal expansion with respect to said unsoftened portions of said body, said bond stress anchorage developing the entire tensile force of said tendon.
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body, said tendon and said body each having a positive coefficient of linear thermal expansion, the coefficient of linear thermal expansion of said tendon being comparable and not greater than the coefficient of linear thermal expansion of said body,
- b. elevating the temperature of said tendon and the region of said body immediately surrounding said tendon to at least the softening temperature of the material of the body so that said tendon elongates and undergoes differential thermal expansion with respect to unsoftened portions of said body,
- c. lowering the temperature of said tendon and the region of said body immediately surrounding said tendon so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said region to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to unsoftened portions of said body as a result of the positive linear thermal expansion of the tendon with respect to said unsoftened portions of said body as a result of the positive linear thermal expansion of the tendon with respect to said unsoftened portions of the body, said bond stress anchorage developing the entire tensile force of said tendon.
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body, said tendon having a greater coefficient of linear thermal expansion than the material of said body,
- b. applying heat to said tendon and the entire body as a unit, the coefficient of liner thermal expansion of said tendon being greater than that of said body, to thereby elevate the temperature of said tendon and said body to at least the softening temperature of the material of the body, so that said tendon elongates and undergoes differential thermal expansion with respect to said body;
- c. lowering the temperature of said tendon and said body so that said tendon contracts with a minimum degree of slippage with respect to said body during and after resolidification of said body to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to said body as a result of its greater coefficient of linear thermal expansion as respects said body, said bond stress anchorage developing the entire tensile force in said tendon.
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body, said tendon having a greater coefficient of linear thermal expansion than the material of said body,
- b. applying heat to said tendon and the region of said body immediately surrounding said tendon selectively, to thereby elevate the temperature of said tendon and said region to at least the softening temperature of the material of the body so that said tendon elongates and undergoes differential thermal expansion with respect to said body,
- c. lowering the temperature of said tendon and the region of said body immediately surrounding said tendon so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said region to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to said body as a result of its greater coefficient of linear thermal expansion as respects said body, said bond stress anchorage developing the entire tensile force in said tendon.
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body;
- b. positioning said tendon and the entire body in an oven, the coefficient of linear thermal expansion of said tendon being greater than that of said body to thereby elevate the temperature of said tendon and said body to at least the softening temperature of the material of the body, so that said tendon elongates and undergoes differential thermal expansion with respect to said body;
- c. lowering the temperature of said tendon and said body so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said body to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to said body as a result of its greater coefficient of linear thermal expansion as respects said body, said bond stress anchorage developing the entire tensile force in said tendon.
A method for producing a prestressed body with an elongate tendon, comprising the steps of:
- a. positioning said tendon in said body;
- b. passing electric current through said tendon, to thereby elevate the temperature of said tendon and the region of said body immediately surrounding said tendon to at least the softening temperature of the material of said body, said tendon having a positive coefficient of linear thermal expansion as respects unsoftened portions of said body, and so that said tendon elongates and undergoes differential thermal expansion with respect to said body
- c. lowering the temperature of said tendon and the region of said body immediately surrounding said tendon so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said region to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to unsoftened portions of said body as a result of its positive coefficient of linear thermal expansion, said bond stress anchorage developing the entire tensile force in said tendon.
A method for producing a prestressed ceramic body with an elongate tendon, comprising the steps of:
- a. positoning said tendon in said body;
- b. positioning said tendon and the entire body in an oven, applying heat to said tendon and said body in said oven and causing electric current to flow through said tendon, then discontinuing applying heat to said tendon and said body in said oven and simultaneously maintaining said electric current flowing through said tendon, to thereby elevate the temperature of said tendon and the region of said body immediately surrounding said tendon to at least the softening temperature of the material of the body, said tendon having a positive coefficient of linear thermal expansion as respects unsoftened portions of said body, and so that said tendon elongates and undergoes differential thermal expansion with respect to said body;
- c. lowering the temperature of said tendon and the region of said body immediately surrounding said tendon so that said tendon contracts with a minimum degree of slippage with respect to said body during and after the resolidification of said region to thereby generate a bond stress anchorage between said tendon and said body to prestress said ceramic body, said tendon seeking to contract with respect to unsoftened portions of said body as a result of its positive coefficient of linear thermal expansion, said bond stress anchorage developing the entire tensile force in said tendon.
A method for prestressing a body of ceramic or cermet material and the like using an elongate tendon extending therethrough, said tendon having a greater coefficient of linear thermal expansion than the material of said body, comprising:
- a. positioning the tendon in the body;
- b. heating the tendon and the region of the body immediately surrounding the tendon until the softening temperature of the body material is reached, and thereby causing the tendon to elongate with respect to the body;
- c. cooling the tendon and the region of the body immediately surrounding the tendon to resolidify such region;
- d. forming a bond stress anchorage directly between the body and the tendon during said step of cooling, said bond transmitting by means of anchorage bond stress the entire prestressing force between the body and the tendon;
- and
- e. further cooling the tendon to thereby tension the tendon and transmit the compressive force through said bond stress anchorage, whereby the body is prestressed.
3 more elements
A method for forming a prestressed body of ceramic material for use in an elevated service temperature, comprising:
- a. selecting a body and a tendon such that the tendon is constructed of a material having a coefficient of linear thermal expansion smaller than that of the material of the body;
- b. positioning the tendon in the body;
- c. bonding the tendon to the body;
- and
- d. elevating the body to a service temperature, thereby causing the body to expand relative to the tendon and become compressed by the tendon.
2 more elements
A method for prestressing a body of ceramic or cermet material and the like with an elongate tendon extending therethrough, said material and tendon being selected so that when said material is softened under heat it will fuse to the tendon on resolidifying, comprising the steps of:
- a. positioning said tendon in said body;
- b. heating said tendon and at least the region of said body immediately surrounding said tendon as a unit in an oven;
- c. selectively heating said tendon by causing electric current to flow through the tendon until said region softens;
- d. subsequently discontinuing heating the tendon and at least the region of said body immediately surrounding the tendon as a unit;
- e. simultaneously with said step of discontinuing, maintaining said tendon and the region of said body immediately surrounding said tendon selectively heated, thereby expanding said tendon with respect to said body;
- f. subsequently cooling said tendon and said region until material in said region resolidifies and fuses directly to said tendon;
- g. forming a bond stress anchorage to the outer wall of said tendon at least at each end thereof, said anchorage being capable of transmitting the entire prestressing force between the body and the tendon through bond stress;
- and
- h. subsequently further cooling said tendon and region to thereby tension the tendon through said bond stress anchorage at each end thereof and apply a corresponding compressive prestressing force to said body.
6 more elements
Dependencies are inferred from the claim text.