Abstract: A rotor assembly comprised of a multiplicity of blades mounted around the periphery of a disk has the blade tips ground to great diametrical precision when the assembly is rotated at a high speed in excess of 1000 rpm in a special grinding process. Individual blade lengths are dynamically measured while the assembly is being ground. These measurements are used to control the grinding process and to also permit accurate assessment of the quality of assemblies in general. A laser triangulation measurement system is used. It is capable of very fast reading of blade length since 3300 or more blades may pass by the measuring point each second.

Abstract: Articles are made of coiled metal sheet which has been thermal mechanically worked so it has a particular texture or crystallographic orientation dominant along its length. The sheet is wound around a mandrel to form a coil and the coil is then hot isostatically bonded to make a monolithic circular article. The article has a circumferential crystallographic orientation which corresponds with that which dominates the length of the sheet.

Abstract: A combustor liner for a gas turbine engine, which has become distorted during use or repair, is restored to its original dimensions by selective heating at two circular locations, accompanied by outward radial replacement. An induction coil is used to heat the liner. When the support ring parts are also replaced, the high temperature mechanical reforming procedure is such that the subsequent distortion which accompanies the welding replacement of support rings is compensated for.

Abstract: The weld zone in Hastelloy X nickel superalloy is thermal mechanically worked by cold working the weld zone to reduce its thickness by about 5-40%, and by annealing at 1120.degree.-1175.degree. C. for one hour to cause recrystallization. Low cycle fatigue properties of laser and gas tungsten arc weld zones are substantially increased.

Abstract: An array of optical fibers is precisely positioned in channels in a head when liquid metal, such as tin-lead solder, is used. This is compared to irregular locating which is obtained with organic resins. A glass fiber is first ion plated with about 1.times.10.sup.-6 m of a metal such as nickel which is wetted by the solder. The fiber is placed loosely in a channel in a metal holder and solder is infiltrated. In an embodiment, strain on the glass fiber where it exits its holder channel is alleviated when the polymer jacket is also ion plated with metal and soldered to the holder.

Abstract: Chromium boron diffusion coatings on nickel iron alloys uniquely provide them with improvement in high cycle fatigue strength (up to 30%) and erosion resistance (up to 15 times), compared to uncoated alloy. The diffused chromium layer extends in two essential concentration zones to a total depth of about 40.times.10.sup.-6 m, while the succeeding boron layer is limited to 50-90% of the depth of the richest Cr layer nearest the surface. Both coatings are applied using conventional pack diffusion processes.

Abstract: When drilling very small diameter holes in workpieces, there is a great tendency for expulsed workpiece material to travel back along the electron beam path, and to deposit as debris within the interior of the gun. The debris is caused to mostly land at a recess in the rim of a rotatable interior shield, positioned adjacent the beam path inside the gun. The deflection angle of the electron beam is precisely adjusted so that the expulsed workpiece material lands in the recess, from when it is removed by a scraper. A tab is placed within the recess at the rim of the shield, and helps remove small amounts of deposit which still adhere to stationary parts of the electron beam gun system adjacent to the shield. In this embodiment, a resilient scraper such as a wire brush, is used to remove adhering debris from the rim of the shield.

Abstract: A method of epitaxially casting single crystal metal articles in molds, which comprises causing the solidification interface velocity vector to rotate through at least 90 degrees, preferably 180-540 degrees, about the axis of overall directional solidification growth. In addition, a mold section has a small passageway configured to prevent line of sight communication between the portion where the seed is contained and the article portion of the mold. Preferably, the passageway is shaped like a helix of 0.8-1.5 turns. A second seed can be formed in the mold of an article made from a first seed, and used to make a second casting. The invention reduces the normal increase in crystallographic variability which would otherwise be associated with such practice.

Abstract: A truncated conical segment is made by the steps of longitudinally welding two pieces of metal, then contour rolling the weldment to preferentially reduce one of the pieces of the weldment more than the other. This provides a skewed trapezoid shape which is then 3-roll formed into a ring having a conical shape. The angle of the cone is a function of the preferential reduction in the second contour rolling step.

Abstract: In shot peening apparatus, a device is provided for sensing shot peening intensity and the uniformity of shot flow. It is basically comprised of a detector plate mounted on a cantilevered arm; torque created at the arm mounting due to the impact of shot is measured with a transducer. The detector is mounted on a structure adapted to translate the detector through a large shot peening zone. The invention is especially suited for assuring consistency in a process wherein uniform spherical shot is gravity accelerated to impact a workpiece with uniform velocity.

Abstract: Disclosed is a method and fixture for applying a thin layer of polymer material to a piece of wavy sheet metal, so that the layer may function as a backer during electron beam drilling. The sheet is drawn to the smooth surface of a fixture using a vacuum, and polymer is flowed across the surface using a curved leveling board, which produces a generally uniform thickness molding. The edges of the backer are molded with a bevel edge by shaped side rails, to provide a relief around the edge of the backer layer. Thus a raised up portion usually occuring at the edge rail will not interfere with the precise spacing which the backer is intended to produce between the sheet and the workpiece holder during electron beam drilling.

Abstract: Disclosed is a method for directional solidification of large single crystal metal alloy castings using multiple seed crystals. Solidification interfaces emanate from the separate seeds, and merge to form a unitary solidification interface which is caused to move through the article. The crystallographic orientation of the seeds is controlled, to avoid unacceptable mismatch of crystal structure orientation where the separate interfaces merge.

Abstract: Plasma flame sprayed ceramic thermal barrier coatings on metal substrates are treated to make the coatings resistant to damage from thermal cycling. The coating and substrate are heated to a temperature in the range of 820.degree.-1150.degree. C. then are quenched in a medium capable of producing a surface heat flux of at least 1.3.times.10.sup.5 watts/m.sup.2. This causes creation of a fine network of cracks extending from the surface of the coating to the surface of the substrate whereby during thermal cycling, buildup of damaging stresses at the coating-substrate interface is avoided.

Abstract: The impact resistance of hot pressed silicon carbide articles is improved by providing thereon a layer of material resulting from the reaction of silicon in a dilute hydrocarbon gas atmosphere. To form the impact absorbing layer of porous silicon carbide, a silicon powder compact is heated at about 1400.degree. C. in a gas stream comprised predominantly of a carrier gas such as hydrogen, with a reactive hydrocarbon gas such as methane. Unitary articles may also be formed.

Abstract: A method for simultaneously shot peening and smoothing includes use of relatively large, smooth, hard, spherical steel shot having a substantially uniform diameter in the range 1-2.5 mm. Titanium workpieces are provided in one step with a compressive stress layer of the order of 0.13 mm and a surface finish of better than 15.times.10.sup.-6 inch AA, compared to conventional peened finishes of the order of 40.times.10.sup.-6 inch AA. Surface finish and peening intensity are inter-related and dependent on shot diameter, mass, velocity, and energy within relatively small limits. The shot diameter is uniform within .+-.0.05 mm; the shot impact velocity is uniform within .+-.4 percent or less, in the range 1.4-12 m/s.

Abstract: A ceramic shell mold for directional solidification of a single crystal metal article has an improved starter section which converts columnar grain growth to single crystal grain growth. The pitch or lead of the helix is chosen so that the separation between adjacent turns of the helix is less than twice the thickness of the layered ceramic shell material which comprises the mold. Thus, when the ceramic shell mold is formed by the repetitive application of layers of ceramic to a wax pattern, the gap between adjacent turns of the helix will be bridged when the mold has reached 50-80% of its final thickness. Then, continued accumulation of ceramic layers bridges the turns of the helix thereby giving it strength. A helical passage diameter in the 8-10 mm range significantly increases single crystal casting yields compared to smaller diameters commonly used heretofore.

Abstract: Disclosed is a liquid mixer having a multiplicity of slotted orifice plates spaced apart along the flow path within a chamber. Liquid passes through and exits from the slots at a 30-60 degree angle to the exit face of the orifice plates, thereby inducing turbulence which causes good mixing. Preferably the slots are radially disposed in circular orifice plates fitted closely within a cylindrical chamber. The radial length L of the slots is preferably five times the slot width T, and the spacing S of the orifice plates is 4-8 times the width. Straight slots are simplest to make but curved slots are preferred. Radial slots in a circular disc are preferred but other orientations are useful. When used for dispersing small volumes of water into oil, water is injected transversely into the oil upstream of the orifice plates, to cause initial droplet formation; and, the oil-water fluid velocity through the slots is kept in the range of 80-1600 feet per second.

Abstract: Disclosed is apparatus and method for electrochemically finishing the edges of airfoils and other thin edged objects. When the edge on an airfoil varies in thickness along its length, a tapered electrode is provided which has both a decreased diameter and increased spacing distance, providing a means for obtaining an edge with a radius proportioned to the thickness. Generally, in the system having an electrode with a unit surface area A, and with an electrode-workpiece surface spacing distance S, both A and S are changed so that the ratio A/S is lowered for electrode portions proximate to edge portions having lowered thickness.

Abstract: Chemical milling of cast superalloys having high tungsten contents is advantageously accomplished with an etchant which consists by volume percent of 40-60 concentrated HNO.sub.3, 0.6-0.8 concentrated HF, .[.30.]..Iadd.40.Iaddend.-70 H.sub.2 O, with which is included at least 0.008 moles/liter CuSO.sub.4 and 0.0016-0.025 moles/liter FeCl.sub.3. Preferably the molar ratio of CuSO.sub.4 to FeCl.sub.3 is 2:1 and etching is accomplished in the range 50.degree.-80.degree. C.