Abstract: Alignment of the [001] crystal axis of a face centered cubic metal with the primary z axis of a single crystal article provides good thermal fatigue resistance along the z axis, and minimizes cracking transverse to the axis. However, significant cracking is still observed parallel the z axis in severe applications. This cracking can be reduced by controlling the secondary crystallographic orientation (i.e., orientation of crystal axes within x-y planes transverse to the z axis), to make the [110] crystal axis tangent to the article surface in the region most prone to thermal fatigue cracking. Algorithims derived from empirical relationships enable calculation of the orientation likely to produce improved fatigue resistance. More durable single crystal gas turbine blades result when the [110] crystal axis is made tangent to the blade surface in the critical crack prone regions just behind the leading edge of the airfoil at about 40-80% of the airfoil span.

Abstract: Disclosed is a process for plasma spraying small metal fibers, to adhere them to the surface of a workpiece, and articles made using the process. The process is especially useful for improving the strength of plasma arc coatings, as well as for improving the bonding of plasma arc coatings to substrates. To make an improved ceramic faced metal article, fibers are sprayed onto the workpiece by injecting fibers into the plasma stream external to the plasma gun nozzle. Then, plasma sprayed ceramic particles are caused to surround the fibers as a matrix. The optional interposition of a removable polymer material on the workpiece surface, after the fibers are sprayed but before the ceramic matrix is sprayed, provides an effective way of providing a low stiffness connector between a low thermal expansion coefficient ceramic material and a high expansion coefficient metal substrate. The connector alleviates strains from thermal expansion differences.

Abstract: End burning gas generators for use either as propulsion systems or means for generating large volume of gases for various purposes such as the generation of the fuel for a ducted rocket engine, the rapid inflation of air bags for personal protection or recovery of submersed items or the expulsion of projectiles from subsurface launch tubes are currently widely utilized. End burning gas generator grains are ignited at one end of a generally cylindrical charge mounted within a combustion chamber which is fixed with a suitable exhaust means. For many of the applications described above, it is desirable that the gas generator burn in a uniform manner such that a constant volume of gas is generated per unit of time so that the chamber pressure and the mass flow rate of gas remain constant.

Abstract: A machine for simultaneously blending and degassing powders under vacuum is comprised of a rotatable blender shell having a heated housing projecting into the interior, coaxial with the axis of rotation of the shell. Powder is heated to a relatively high temperature when it contacts the heater, while the shell remains comparatively cooler.

Abstract: Thin edged workpieces are chemically milled to remove material uniformly from their surfaces by tumbling the workpieces in a barrel in which is contained a sufficient volume of inert polymer particulate media. Titanium airfoils for turbomachinery are able to have an oxidized surface layer removed without suffering small nicks and other damage to their critically shaped edges.

Abstract: The magnetic actuator part of a gas safety valve is constructed with a C-shaped insulator which grips the base portion of a U-shaped magnet that is fastened to a base. The base has welded to it a projecting contact pin. The coil of the electromagnet is fusion welded at both its ends: at its first end it is attached to a plate which connects to the center pin; at its second end it is attached to the contact pin to which it lies transverse. The construction facilitates good electrical connections between dissimilar materials and permits rapid assembly by a robot.

Abstract: A ceramic insert for a tool holder is in the shape of a tapered cylinder wherein the diameter increases outwardly along the insert length, from a first end to a second end. The second or upper end of the insert has a bevel around its circumference; the intersection of the bevel and tapered sidewall of the cylinder provide a cutting edge which has a negative rake and relief angle which are desirably constant around the insert. Thus the insert may be mounted on a neutral plane in a tool holder and a tool will cut equally well in any direction along a 180.degree. arc. Various engagement and clamping means are used to hold the insert in place in the tool holder.

Abstract: Insulating material is applied in selected mold surfaces and in critical thicknesses to prevent cracking of the mold and casting therein during the heating and cooling steps of high rate directional solidification processes.

Abstract: The ends of gear teeth are chamfered using an arcuate motion cutter having a complex cross sectional shape. In an improvement of the prior trial and error techniques, the cutter shape is made correctly the first time using an algorithm which includes determining certain s-dimensions produced on a chamfer by a set of tool dimensions; comparing these to the desired maximum, minimum and nominal chamfer widths, and; then iteratively optimizing the set of tool dimensions to minimize the differences.

Abstract: Directional solidification of a single crystal superalloy article may be accomplished using a mold with a starter section, and a selector section to convert columnar growth from the starter into single crystal growth. In such a process, the deviation of [001] crystallographic orientation with respect to the longitudinal axis of the article being formed is reduced from 9 degrees to 5 degrees by controlling the heat transfer in the starter section. A stepped starter section, wherein the lower subsection has a volume of 52-98% of the total starter volume, and wherein the upper subsection is relatively small in lateral dimension, has been found most useful. When the solidification interface moves into the smaller width upper subsection, it becomes more nearly planar, and results in improved columnar growth in the starter, and in reduction in the crystallographic deviation of the article.

Abstract: Polymer coatings having high solids content and containing mica pigments are applied with uniform appearance when the liquid layer which is deposited on an article is greater in thickness than the nominal maximum length of the mica platelets. Coatings which contain 0.01-5 weight percent mica having up to 60 micrometers maximum platelet length are produced in thicknesses of 0.045-0.076 mm. The coatings are best applied by a conventional turbobell rotary atomizer.

Abstract: Chemical milling of the commercial gamma-gamma prime nickel superalloy IN-100 is carried out by using an aqueous solution comprised of 32.5-85 volume percent HCl, with other ingredients proportioned on the HCl, preferably 40 ml/l nitric acid, 0.0141 M/l metal sulfate ion, 0.0326 M/l metal chloride ion, 0.0168 M/l alkali metal ion and 0.0073 M/l citric acid. The chemical milling is particularly effective in uniformly removing a small amount of surface layer without any deleterious attack. It hereby is useful to improve the effectiveness of surface penetrant inspection, to find small flaws which would otherwise be concealed by a worked surface layer.

Abstract: To make vane airfoils for an axial flow compressor metal strip is first contour rolled to a cross section comprised of two opposing airfoils separated by a center rib, where one of the faces of the strip is kept planar. The rib is used to guide the strip into dies where it is notched and slotted to define individual airfoils. Next, die stamping makes concave the planar surface of each airfoil.

Abstract: A single crystal nickel base superalloy component, such as a gas turbine blade (20, 28) is mechanically deformed at elevated temperature to improve the yield strength of a portion which is used at temperatures below 800.degree. C., compared to a portion which is used at a higher temperature. A blade (20) has a root (22) which is deformed by 2-14% at 700.degree.-1100.degree. C. and an airfoil (24) which is not deformed. The root yield strength is increased 15-50% while the airfoil creep strength is maintained.

Abstract: Electrochemical machining of ceramic particulate and metal matrix surfaces, and of other uneven or discontinuous surfaces, is conducted using an electrode which has a porous metal working face. Relatively low electrolyte pressures of the order of 5 kPa and low flow rates of the order of 6 ml/s/cm.sup.2 of electrode surface are used. Preferably the electrode face is made of sintered powder. Facing the electrode upward and the workpiece surface downward enables machining of workpieces without unwanted flow of electrolyte onto areas away from the machined surface.

Abstract: A switch especially useful for interrupting high frequency induction heating currents is comprised of mating conical shaped contacts. The contact parts of the switch are water cooled by internal cooling channels which are not affected by making or breaking of the switch. The opposing contacts are mounted on separable pieces of the switch; when the clamp is released one side of the switch can be freely separated from the first part. Thus, inflexible high power electrical connections can be made and boken in a vacuum environment through physical movement of the coil and load.

Abstract: Apparatus and method for degassing fine powders of metals are disclosed. A vertical shell having a series of baffle plates inclined at an angle of repose is used to induce a serpentine path for the powder. The shell is subjected to suitable conditions of vibration temperature and pressure to maintain the desired flow rate and gas separation. Conditions of mesh size, pressure temperature, angle of repose as well as equipment configuration are discussed.

Abstract: Single crystal nickel base superalloys of the gamma-gamma prime type are strengthened by deforming them 2-14% at temperatures in the range 700.degree.-1100.degree. C. Yield strength will be increased typically by 25-50%, depending on the crystallographic orientation. Careful control of parameters is necessary to obtain the strengthening while avoiding recrystallization. The metal is first homogenized and provided with a fine gamma prime deformation; strain rates in the range of 10.sup.-1 cm/cm/sec or less are used.

Abstract: Disclosed are coatings which are improved by a special peening process. Uniform sized spherical steel shot, in the range 1-2.5 mm is impacted at uniform low velocities onto a coated workpiece. Peening intensities are in the range 0.30-0.60 mm N. MCrAlY high temperature coatings are particularly improved, with densities of the order of 99 percent. Physical vapor desposited coatings have surface finishes of the order of 30.times.10.sup.-6 inch AA (Arithmetic Average) and plasma sprayed coatings have finishes of the order of 100.times.10.sup.-6 inch AA compared to unpeened finishes of 50-60.times.10.sup.-6 inch AA and 200-300.times.10.sup.-6 AA respectively.

Abstract: Blade tips of a turbine rotor assembly are ground to precision dimensions of .+-.0.025 mm (.+-.0.001 inch) when the assembly is rotated at high speed during grinding. The speed should be sufficient to produce on the blades a radial acceleration of at least 700 times the force of gravity (6,900 m/s.sup.2). For compressor rotors the direction of rotation should be such that the blades move toward their concave side, and the speed should be sufficient to produce an axial flow. High resultant tip velocities are compensated for when dry grinding titanium alloys by moving the grinding media in the same direction as the tangential velocity at the point of contact. Burrs are eliminated by feeding at a very slow rate, of the order of 0.0004 mm/s when the final dimension is approached.