High temperature ultrasonic transducer

Claim 2

An ultrasonic transducer for use in a high temperature environment comprising in combination: a support frame; a crystal holder supported by and movable relative to said support frame, said holder having a support surface; a layer of electrically insulating material on said crystal holder support surface; a piezoelectric crystal including electrically conductive front and back surfaces thereon; first means for biasing said back surface of said crystal into engagement with said layer of insulating material on said crystal holder support surface; second means for biasing said crystal holder in the direction of said crystal front surface, whereby said crystal front surface is presented for contact with an acoustically conductive medium in the high temperature environment; and means for connecting said crystal in an electrical circuit.

Claim 3

The apparatus as in claim 1 wherein said layEr of insulating material on said crystal holder support surface is a coating of ceramic material bonded thereto.

Claim 4

The apparatus as in claim 2 wherein said ceramic material is selected from the group consisting of magnesium oxide, aluminum oxide, zirconium oxide and alumina titania oxide.

Claim 5

The apparatus of claim 1 wherein said first and second biasing means are first and second coil springs respectively, said first spring acting in tension between the back surface of said crystal and said support frame and said second spring acting in compression between said crystal holder and said support frame.

Claim 6

The apparatus as in claim 4 wherein said first spring is electrically conductive and insulated from said support frame to provide a first electrical path to said conductive back surface of said crystal and conductive means including said support frame provide a second electrical path to said conductive front surface of said crystal for connecting said crystal in an electrical circuit.

Claim 7

An ultrasonic transducer for use in a high temperature environment comprising: a support frame including a crystal holder supported thereby; a layer of electrically insulating material disposed on a support surface of said crystal holder; a piezoelectric crystal having front and back surfaces with electrically conductive coatings thereon; spring means acting between said crystal and said frame for urging said crystal conductive back surface into supported contact with said insulating material on said crystal holder support surface; and means for connecting said front and back electrically conductive crystal surfaces into an electrical circuit.

Claim 8

An ultrasonic transducer for use in a high temperature environment comprising: a support frame including a crystal holder supported thereby; a layer of electrically insulating material disposed on a support surface of said crystal holder; a piezoelectric crystal having front and back surfaces with electrically conductive coatings thereon; spring means acting between said crystal and said frame for urging said crystal conductive back surface into supported contact with said insulating material on said crystal holder support surface; and means for connecting said front and back electrically conductive crystal surfaces into an electrical circuit.

Claim 9

In an ultrasonic inspection system wherein ultrasonic energy is coupled between an ultrasonic transducer and a test piece in a high temperature environment said ultrasonic transducer comprising: a support frame adapted to be fixedly positioned in close proximity with the surface of said test piece in said high temperature environment; a crystal holder supported by said frame in movable relationship therewith toward and away from said surface of said test piece; a layer of electrically insulating material disposed on a surface of said holder; a piezoelectric crystal having first and second electrodes on opposite surfaces thereof; first means urging said first electroded surface of said crystal into supported contact with said crystal holder, said first electrode contacting only said insulating material on said crystal holder whereby to be electrically isolated therefrom; second means urging said crystal holder toward said test piece surface whereby said second electroded surface of said crystal is presented for acoustical contact with said surface of said test piece; and circuit means communicating electrically with said first and second electrodes to complete an electrical circuit including said crystal.

Claim 10

In an ultrasonic inspection system wherein ultrasonic energy is coupled between an ultrasonic transducer and a test piece in a high temperature environment said ultrasonic transducer comprising: a support frame adapted to be fixedly positioned in close proximity with the surface of said test piece in said high temperature environment; a crystal holder supported by said frame in movable relationship therewith toward and away from said surface of said test piece; a layer of electrically insulating material disposed on a surface of said holder; a piezoelectric crystal having first and second electrodes on opposite surfaces thereof; first means urging said first electroded surface of said crystal into supported contact with said crystal holder, said first electrode contacting only said insulating material on said crystal holder whereby to be electrically isolated therefrom; second means urging said crystal holder toward said test piece surface whereby said second electroded surface of said crystal is presented for acoustical contact with said surface of said test piece; and circuit means communicating electrically with said first and second electrodes to complete an electrical circuit including said crystal.

Claim 11

The apparatus as in claim 7 wherein said test piece is ferromagnetic and said support frame includes magnet means affixed thereto for magnetically engaging said frame with the surface of said test piece.

Claim 12

The apparatus of claim 7 wherein: said support frame includes a forward portion for contact with the surface of said test piece; said crystal holder is movable between a forward exposed position which extends the forward surface of said crystal at least to the forward extent of said support frame and a protected position in which the forward surface of said crystal is withdrawn rearwardly of the forward extent of said support frame; said second means urge said crystal holder and crystal toward said exposed position; and including means for releasibly locking said crystal holder into said withdrawn protected position.

Claim 13

The apparatus of claim 7 wherein said support frame includes a first portion for fixed positioning in close proximity with the surface of said test piece and a second portion supporting said crystal holder and movable relative to sAid support frame first portion to vary the angle of said crystal relative to the surface of said test piece.

Claim 14

The apparatus of claim 10 wherein: said first portion of said support frame includes a cylindrical member having its axis substantially normal to the surface of said test piece; said crystal holder is of circular cross-section slightly smaller than and movable within the inner diameter of said cylindrical member, said crystal holder being supported by rigid means secured thereto and pivotably depending from said second portion of said support frame; and said support frame second portion is spaced from the surface of said test piece and is movable transversely of the axis of said cylindrical member of said first portion, whereby to vary the angle of said crystal relative to the surface of said test piece.

Claim 15

The apparatus of claim 11 wherein said test piece is ferromagnetic and said cylindrical member of said support frame first portion is a magnet.