Abstract: Linear friction welding is used to join dissimilar materials, namely a first workpiece formed of a high wear resistant material and a second workpiece formed of a base material. A compressive force is applied and a friction force is generated between the first and second workpieces. A solid-state joint is formed between the first and second workpieces. The high wear resistant material can be a tool steel, and the base material can be a low alloy steel or a carbon steel. The composite assemblies can be used for mining wear applications.

Abstract: A system for cold gas dynamic spraying of particulate material has a de Laval nozzle and two or more radial particle inlets located between the throat and the outlet of the nozzle, the two or more particle inlets arranged symmetrically around a linear flow path of the nozzle. Blocking of the inlets is reduced by controlling pressure of particle carrier gas to provide a stable particulate material injection pressure before and during introduction of working gas into the nozzle, and/or by clearing the particle inlets of residual particles after a spraying process. Such a system and associated method combines benefits of both downstream and upstream cold gas spray systems. Further, a nozzle for spraying particulate material having a cross-sectional shape that is narrower in a middle section compared to edge sections provides coatings with superior cross-sectional profiles.

Abstract: A system for cold gas dynamic spraying of particulate material has a de Laval nozzle and two or more radial particle inlets located between the throat and the outlet of the nozzle, the two or more particle inlets arranged symmetrically around a linear flow path of the nozzle. Blocking of the inlets is reduced by controlling pressure of particle carrier gas to provide a stable particulate material injection pressure before and during introduction of working gas into the nozzle, and/or by clearing the particle inlets of residual particles after a spraying process. Such a system and associated method combines benefits of both downstream and upstream cold gas spray systems. Further, a nozzle for spraying particulate material having a cross-sectional shape that is narrower in a middle section compared to edge sections provides coatings with superior cross-sectional profiles.

Abstract: A system for cold gas dynamic spraying of particulate material has a de Laval nozzle and two or more radial particle inlets located between the throat and the outlet of the nozzle, the two or more particle inlets arranged symmetrically around a linear flow path of the nozzle. Blocking of the inlets is reduced by controlling pressure of particle carrier gas to provide a stable particulate material injection pressure before and during introduction of working gas into the nozzle, and/or by clearing the particle inlets of residual particles after a spraying process. Such a system and associated method combines benefits of both downstream and upstream cold gas spray systems. Further, a nozzle for spraying particulate material having a cross-sectional shape that is narrower in a middle section compared to edge sections provides coatings with superior cross-sectional profiles.

Abstract: A method of modifying a surface of a casting involves providing a casting mould; placing a perforated mask with the mould to define a masked area of the mould; spray-coating the masked area of the mould with a coating material selected for forming a surface layer on the casting; introducing a liquid casting material to the mould; and, solidifying the liquid casting material to form a surface modified casting. The present method reduces the tendency for the coating material to spall from the mould and permits the formation of thicker coating layers on the mould. Thicker and better quality surface layers may be formed on castings.

Abstract: A method of modifying a surface of a casting involves providing a casting mould; placing a perforated mask with the mould to define a masked area of the mould; spray-coating the masked area of the mould with a coating material selected for forming a surface layer on the casting; introducing a liquid casting material to the mould; and, solidifying the liquid casting material to form a surface modified casting. The present method reduces the tendency for the coating material to spall from the mould and permits the formation of thicker coating layers on the mould. Thicker and better quality surface layers may be formed on castings.

Abstract: A ceramic mould slurry is disclosed for forming moulds and metal castings of improved surface quality. The slurry comprises a binder, a gelling agent, a first refractory material having a density of &rgr;1 and a mean particle size of &agr;1, and a second refractory material having a density of &rgr;2 and a mean particle size of &agr;2, wherein &rgr;1>&rgr;2 and &agr;1<&agr;2. The denser refractory material migrates downward through the slurry toward the upward-facing mould surface, thereby allowing formation of a smooth and accurate surface.

Abstract: A ceramic mould slurry is disclosed for forming moulds and metal castings of improved surface quality. The slurry comprises a binder, a gelling agent, a first refractory material having a density of &rgr;1 and a mean particle size of &agr;1, and a second refractory material having a density of &rgr;2 and a mean particle size of &agr;2, wherein &rgr;1>&rgr;2 and &agr;1<&agr;2. The denser refractory material migrates downward through the slurry toward the upward-facing mould surface, thereby allowing formation of a smooth and accurate surface.

Abstract: A method of making a mold directly from the object to be molded is disclosed. The object is placed within a walled enclosure having a closed bottom and open top. A plurality of elongated metal rod elements is vertically introduced and packed into the enclosure in vertical contact with said object and side by side contact with one another. An infiltration agent, such as a liquid resin or metal, is introduced over the elongated metal rod elements and allow to permeate into the spaces between the rod elements. The mass consisting of the liquid infiltration agent and the elongated metal elements is allowed to solidify into a mold which is removed from the object.

Abstract: A method of making a mould directly from the object to be moulded is disclosed. The object is placed within a walled enclosure having a closed bottom and open top. A plurality of elongated metal rod elements is vertically introduced and packed into the enclosure in vertical contact with said object and side by side contact with one another. An infiltration agent, such as a liquid resin or metal, is introduced over the elongated metal rod elements and allow to permeate into the spaces between the rod elements. The mass consisting of the liquid infiltration agent and the elongated metal elements is allowed to solidify into a mould which is removed from the object.