Abstract: A microscopy-thermal wave microscopy apparatus for measuring crack propagon resistance based on the lateral crack system induced by forming a hardness indentation in an opaque material the resistance and crack extent providing a quantitative measure of the spalling propensity of the opaque material.

Abstract: A novel control method and attendant apparatus for controlling other various methods/processes by utilizing a photoacoustic effect principle, whether or not the other various processes are with regard to solid or non-solid fluid media, but which other various processes use and require control of a primary excitation high energy beam and related beam-modulating and monitoring apparatus for establishing and detecting a photoacoustic effect. This method and apparatus require the use of appropriate beam generating and beam-generating power control means for controlling such an energy beam, the latter of which may be of the type including laser beams, microwave beams, x-rays and other electromagnetic wave beams, as well as ion, electron, particle, and molecular beams.

Abstract: Novel methods for the continuous manufacturing of radial flow ceramic matal rotor bodies for rotary type regenerator heat exchange apparatus, and novelly constructed rotor bodies made by and reflecting the characteristics of the novel methods.The novel methods basically comprise preferably the continuous assembling of predetermined numbers of axially arranged, sequential, radially grooved layers of unfired ceramic media, with sequentially touching layers coacting to collectively form outwardly flaring fluid gas passageways, disposed in a 360.degree. continuous radially oriented manner extending uniformly around the open center passageway through the rotor body.

Abstract: A method of sealing the pores in wall structures formed of sintered ceramic owders, especially silicon nitride or silicon carbide. The sealing operation is performed by pumping two reactant gases into the pores of the wall structure from opposite sides of the structure. As the gases meet one another within the pores they chemically react to form a solid ceramic sealant material, e.g., silicon nitride or silicon carbide. The reactant gases are selected so that the in situ-formed sealant corresponds chemically to the wall structure material.

Abstract: A process of and related apparatus for achieving laser annealing of film-like surface layers of chemical vapor deposited silicon nitride and silicon carbide to relieve their inherent residual stresses. A laser beam is used to anneal the layers, in conjunction with a photoacoustic gas cell and related beam modulating means for utilizing a photoacoustic effect principal for monitoring, detecting and effectuating beam control as needed during the laser annealing process.

Abstract: A novel transducer able to detect ultrasonic surface waves over a wide frency band. The transducer is essentially a grid or series of bars connected in parallel or series. The sensitivity of the transducer increases proportionally with frequency for constant surface wave amplitude. The transducer detects surface waves by providing a resistance change across the transducer output terminal proportional to the surface wave strain. The output voltage can be calibrated to give a direct reading of the surface wave amplitude. The coupling problems which are inherent in most transducer configurations are drastically reduced for this strain sensitive detector. The modulation of the grid excitation voltage provides a means for mixing two signals by giving the direct product of the signals in time. Complicated filtering functions can be built into the grid detector by varying the bar spacing in a manner analogous to the piezoelectric interdigital grid transducer.