Abstract: A method of monitoring the condition of a thermal barrier coating on a turbine blade or vane during operation of the turbine is provided. The method includes providing a means for receiving acoustic output of the blade or vane during operation of the turbine and monitoring the acoustic output over time, to determine the condition of the thermal barrier coating on the blade or vane. The acoustic output arises from a force on the blade or vane, such as that due to impact of particles, a pulse of gas pressure or constant gas flow. An apparatus employing the above method for monitoring the condition of the thermal barrier coating during operation of the turbine, is also provided.

Abstract: A pressure sensor (52) for a harsh environment such as the combustion chamber (58) of a gas turbine engine (50). The pressure sensor includes an acoustic waveguide (60) having a sensing portion (66) exposed to the combustion gas in the combustion chamber. Modulations in an acoustic signal passing through the acoustic waveguide are sensed and correlated to pressure fluctuations in the combustion gas. The sensing portion of the waveguide includes a core acoustic waveguide element (42) covered by a coating material (44). The coating material not only protects the core from the harsh environment, but it also improves the efficiency of the transfer of energy from the combustion gas into the waveguide because it provides a stepped transition from the acoustic impedance of the gas to the acoustic impedance of the core material. The protective coating may have a plurality of layers (46, 48) and/or it may include a graded material (78, 80) having an acoustic impedance value that varies across its depth.

Abstract: A method and apparatus for monitoring the condition of the thermal barrier coating on turbine blades and vanes is provided. The coating is monitored with ultraviolet sensors which can detect ultraviolet radiation emitted from electrical discharges and glow coronas at the surface of the blades and vanes. Such electrical glow discharges and coronas are the result of friction electricity found at the surface of blades and vanes, and are also due to the high pressure, temperature and velocity conditions within the turbine. As the thermal barrier coating deteriorates, the electrical discharges and glow coronas and associated UV emissions decrease in magnitude or have other characteristic changes, thus permitting monitoring of the corona to detect changes in the coating over time.

Abstract: A pressure sensor (52) for a harsh environment such as the combustion chamber (58) of a gas turbine engine (50). The pressure sensor includes an acoustic waveguide (60) having a sensing portion (66) exposed to the combustion gas in the combustion chamber. Modulations in an acoustic signal passing through the acoustic waveguide are sensed and correlated to pressure fluctuations in the combustion gas. The sensing portion of the waveguide includes a core acoustic waveguide element (42) covered by a coating material (44). The coating material not only protects the core from the harsh environment, but it also improves the efficiency of the transfer of energy from the combustion gas into the waveguide because it provides a stepped transition from the acoustic impedance of the gas to the acoustic impedance of the core material. The protective coating may have a plurality of layers (46, 48) and/or it may include a graded material (78, 80) having an acoustic impedance value that varies across its depth.

Abstract: A foreign object impact sensor for use with combustion turbines utilizes a passive acoustic waveguide within the turbine to receive acoustic signals from foreign object impact. The magnitude of these signals is displayed and or stored using a lighted display or other suitable indicating device. The information is also recorded and stored, so that a spectrum signature can be obtained from Fourier analysis.

Abstract: A method and apparatus for monitoring the condition of the thermal barrier coating on turbine blades and vanes is provided. The coating is monitored with ultraviolet sensors which can detect ultraviolet radiation emitted from electrical discharges and glow coronas at the surface of the blades and vanes. Such electrical glow discharges and coronas are the result of friction electricity found at the surface of blades and vanes, and are also due to the high pressure, temperature and velocity conditions within the turbine. As the thermal barrier coating deteriorates, the electrical discharges and glow coronas and associated UV emissions decrease in magnitude or have other characteristic changes, thus permitting monitoring of the corona to detect changes in the coating over time.

Abstract: A method of monitoring the condition of a thermal barrier coating on a turbine blade or vane during operation of the turbine is provided. The method includes providing a means for receiving acoustic output of the blade or vane during operation of the turbine and monitoring the acoustic output over time, to determine the condition of the thermal barrier coating on the blade or vane. The acoustic output arises from a force on the blade or vane, such as that due to impact of particles, a pulse of gas pressure or constant gas flow. An apparatus employing the above method for monitoring the condition of the thermal barrier coating during operation of the turbine, is also provided.

Abstract: A foreign object impact sensor for use with combustion turbines utilizes a passive acoustic waveguide within the turbine to receive acoustic signals from foreign object impact. The magnitude of these signals is displayed and or stored using a lighted display or other suitable indicating device. The information is also recorded and stored, so that a spectrum signature can be obtained from Fourier analysis.

Abstract: A method and apparatus for monitoring the condition of a thermal barrier coating on the vanes and blades of a combustion turbine relies on a piezoelectric or electrostrictive effect, or tribo-charging generated within the coating. Gas flowing through the turbine will apply pressure to the vanes and blades, resulting in a strain on the blades and vanes, and causing friction as it passes the vanes and blades. An electric current is generated between the coating and vane or blade, either by a pressure-induced piezoelectric effect, a strain-induced electrostrictive effect, or friction-induced tribo-charging. This current causes a radio frequency signal, which can be detected by a high temperature antenna as the blade passes the antenna. One blade may be intentionally designed to produce a signal different from the remaining blades, thereby becoming a marking blade. After amplification and filtering, the radio signals may be analyzed and stored.

Abstract: A method and apparatus for monitoring the condition of a thermal barrier coating on the vanes and blades of a combustion turbine relies on a piezoelectric or electrostrictive effect, or tribo-charging generated within the coating. Gas flowing through the turbine will apply pressure to the vanes and blades, resulting in a strain on the blades and vanes, and causing friction as it passes the vanes and blades. An electric current is generated between the coating and vane or blade, either by a pressure-induced piezoelectric effect, a strain-induced electrostrictive effect, or friction-induced tribo-charging. This current causes a radio frequency signal, which can be detected by a high temperature antenna as the blade passes the antenna. One blade may be intentionally designed to produce a signal different from the remaining blades, thereby becoming a marking blade. After amplification and filtering, the radio signals may be analyzed and stored.

Abstract: A system for online monitoring the condition of a thermal barrier coating on the vanes and/or blades of a combustion turbine, or other forms of component deterioration affecting the acoustic properties of the vanes and/or blades. The system begins with a signal generator for transmitting a signal to an acoustic transmitter, and then to an acoustic waveguide secured within the turbine, adjacent to a vane. Acoustic waves passing through the vane's coating will have a certain magnitude and velocity when passing through an intact coating, which will change as the coating deteriorates. Additional variation of the acoustic wave will occur due to pressure pulses from passing blades, with the magnitude of the pressure pulses increasing as the blade's coating deteriorates. The acoustic waves are then received by a second acoustic waveguide.

Abstract: A system for online monitoring the condition of a thermal barrier coating on the vanes and/or blades of a combustion turbine, or other forms of component deterioration affecting the acoustic properties of the vanes and/or blades. The system begins with a signal generator for transmitting a signal to an acoustic transmitter, and then to an acoustic waveguide secured within the turbine, adjacent to a vane. Acoustic waves passing through the vane's coating will have a certain magnitude and velocity when passing through an intact coating, which will change as the coating deteriorates. Additional variation of the acoustic wave will occur due to pressure pulses from passing blades, with the magnitude of the pressure pulses increasing as the blade's coating deteriorates. The acoustic waves are then received by a second acoustic waveguide.

Abstract: A non-reflecting, wave-absorbing structure absorbs sound, radio and radiation wave. The non-reflecting, wave-absorbing structure combines an outer non-reflecting wave structure and a wave-absorbing portion. The outer non-reflecting wave structure allows for the transmission of the wave therethrough without appreciable reflection and the wave-absorbing material absorbs substantially all of the transmitted wave. In the case the wave to be absorbed in a sound wave, the wave-absorbing material is preferably an epoxy in a chemical state of gelatinization which is prevented from reaching a state of cure.

Abstract: A device is disclosed which allows an object to be tuned to an incoming sound wave magnitude and wavelength, such that the sound wave will alternatively be passed therethrough without detectable reflection or be completely reflected. The apparatus is intended to be mounted within a hollow object and adjust the perceived distance between the exterior walls of that object to mimic a single thick wall. A signal processing means is supplied which detects the sound wave magnitude and wavelength impinging on the wall facing the sound wave source. The wavelength is passed to the signal processing means, which transmits a complimentary signal to the second wall of the hollow object. The complimentary signal allows the hollow object to resonate as a whole as if it were a solid of a thickness much different from its actual thickness, allowing the sound wave to pass undisturbed therethrough or be reflected therefrom.

Abstract: Disclosed in an emulsion having a discontinuous phase that consists of a water dispersed or water emulsified epoxy resin in water having at least two epoxide groups, a water soluble salt of an imide compound having at least one carboxyl group, and a crosslinking agent; the discontinuous phase has excess epoxide functionality. The continuous phase is water. A method of forming a coating on a conductive substrate is also disclosed. The substrate and an electrode are immersed into the emulsion and a direct current is applied between the substrate and the electrode to electrophoretically deposit a coating on the substrate of the epoxy resin, the imide compound, and the crosslinking agent. The substrate is removed from the emulsion and is heated to a temperature sufficient to cure the coating.

Abstract: Disclosed is a composition comprising about 5 to about 95 phr of a polyepoxide or other resinous component, about 20 to about 90% of an aprotic solvent, about 5 to about 95 phr of a polyimide having sufficient amic acid functionality to be soluble in the solvent, and sufficient water to hydrolyze the polyimide. A laminate is made from the composition by heating it until the amic acid functionality is substantially eliminated, then impregnating a fibrous substrate with the composition, heating the impregnated substrate to evaporate the solvent and B-stage the composition and form a prepreg, forming a stack of the prepregs, and heating and pressing the stack of prepregs to cure the composition. A wire enamel can also be made from the composition.

Abstract: Disclosed is a composition comprising about 5 to about 95 phr of a polyepoxide or other resinous component, about 20 to about 90% of an aprotic solvent, about 5 to about 95 phr of a polyimide having sufficient amic acid functionality to be soluble in the solvent, and sufficient water to hydrolyze the polyimide. A laminate is made from the composition by heating it until the amic acid functionality is substantially eliminated, then impregnating a fibrous substrate with the composition, heating the impregnated substrate to evaporate the solvent and B-stage the composition and form a prepreg, forming a stack of the prepregs, and heating and pressing the stack of prepregs to cure the composition. A wire enamel can also be made from the composition.

Abstract: The invention discloses a polyfunctional imide-containing phenolic imide which is the reaction product of a polyanhydride having at least three anhydride groups and aromatic compound having a single aromatic primary amine group. A varnish is prepared by the addition of an epoxy crosslinking agent to the imide. Fibrous substrates can be impregnated with the varnish and partially cured to prepare prepregs, and stacks of prepregs can then be heated and pressed to prepare laminates or printed circuit boards.

Abstract: Disclosed is a composite of a polyaramid woven fabric and a resin. The resin contains water, a water-based emulsion of an epoxy selected from the group consisting of diglycidyl ethers of bisphenol A, diglycidyl ethers of bisphenol F, novolacs, and mixtures thereof, water-compatible curing agents for the emulsion, and a water-compatible catalyst for the emulsion. The emulsion can be cured to the B-stage to form a prepreg and prepregs can be stacked with copper sheets and heated and pressed to form a laminate for use in making a printed wiring board.

Abstract: Disclosed is a water-based thermosetting epoxy composition of a water compatible epoxy resin, about 5 to about 35%, based on a total solids, of a water compatible impact modifier, about 1.5 to about 7%, based on the weight of the epoxy resin, of a water compatible epoxy hardener, up to about 0.3%, based on the weight of the epoxy resin, of a catalyst, and sufficient water to provide a viscosity of about 100 to about 500 centipoises. The impact modifier is a copolymer of about 10 to about 60% ethylene, propylene, or mixtures thereof, and about 40 to about 90% vinyl acetate, vinyl chloride, or mixtures thereof. Also disclosed are laminates prepared from this composition and a method of preparing them.