Abstract: A method for nondestructive/noncontact detection of alpha case on a surface of a workpiece made of titanium or a titanium-based alloy. Infrared radiation is reflected off of a selected portion of the workpiece surface and sensed by a detector which may comprise a scanning infrared radiometer, an infrared camera, or a spot radiometer. The presence of any alpha case in the selected portion of the workpiece surface is detected by comparing the intensity of the reflected infrared radiation to a predetermined intensity known to be indicative of the absence of alpha case. An image of the reflected infrared radiation may be created and the step of detecting the presence of alpha case may include the step of comparing the intensity of the reflected infrared radiation within the image to the predetermined intensity. According to a preferred embodiment, a target may be disposed between the source of the infrared radiation and the workpiece surface so as to create a predetermined pattern within the image.

Abstract: A method and apparatus for inspecting a channel through a workpiece or cooling holes through the surface of a gas turbine engine are disclosed. The gas turbine engine blade is mounted in a fixture such that a heated gas may be forced into the hollow interior of the blade during a heat-up cycle, and after a predetermined period of time, a solenoid valve switches to shut off the heated gas and to permit a chilled gas to be forced into the hollow interior of the blade for a cool-down cycle. An imaging infrared radiometer generates a series of images of the blade during both the heat-up and cool-down cycles. A selected group of parameters are determined from the series of images generated by the IR radiometer and defects within the cooling holes may then be detected by analyzing the parameters, such as a transient response of the infrared signature of the cooling holes during both the heat-up and the cool-down cycles.

Abstract: A method and apparatus for detecting a defect in a workpiece are disclosed. The workpiece is positioned with a surface of the workpiece to be inspected in an optical path of an infrared radiation detector. A selected portion of the workpiece is heated by scanning with electromagnetic radiation for a selected duration to cause an increase in radiance from any defect present in the selected portion. Any defects, present in the workpiece selected portion, which may cause a failure of the workpiece, may be detected and distinguished from minor surface anomalies by analyzing a transient response of the irradiance received by the infrared radiation detector.

Abstract: In the present invention, a discrete region of the TBC is heated, as by applying a controlled quantity of laser energy onto the region for a time interval. Then, the radiant thermal energy of a region outside the laser strike region is measured at a predetermined time following the termination of the laser pulse. The intensity of this measured radiant energy is then compared with the radiant intensities which have been experimentally obtained from known thickness specimens and the thickness is inferred therefrom.

Abstract: In the present invention, the temperatures of cooling passages in a gas turbine engine blade are changed, as by forcing a heated gas through them. The infrared signatures of the channels are measured during the initial temperature transient of the channels and the signatures are compared with a reference. The reference may be the signature of other channels on the same blade.

Abstract: In the present invention, a discrete region of the TBC is heated, as by applying a controlled quantity of laser energy onto the region for a time interval. Then, the radiant thermal energy of a region outside the laser strike region is measured at a predetermined time following the termination of the laser pulse. The intensity of this measured radiant energy is then compared with the radiant intensities which have been experimentally obtained from known thickness specimens and the thickness is inferred therefrom.