33 results about "Residual porosity" patented technology

Systems and methods for the fabrication of prepregs possessing enhanced ability for the removal of gases from within prepregs and prepreg layups prior to and / or during at least a portion of consolidation and cure process to form composite structures are disclosed. In certain embodiments, perforations of selected configurations may be introduced into the prepregs prior to, during, and after layup. The perforations provide routes for gases trapped within and between the perforated prepregs and prepreg lay-ups to escape during consolidation and cure process, reducing the residual porosity within the resulting composite. For example, composites having residual porosities less than 10 vol. %, on the basis of the volume of the composite, may be achieved in this manner.

The method is suitable for the manufacture of flat or shaped titanium aluminide articles and layered metal matrix composites such as lightweight plates and sheets for aircraft and automotive applications, thin cross-section vanes and blades, composite electrodes, heat-sinking lightweight electronic substrates, bulletproof structures for vests, partition walls and doors, as well as for sporting goods such as helmets, golf clubs, sole plates, crown plates, etc. The method includes the following steps: (a) forming a porous preform of the reactive powder alloy or a porous multi-layer composite preform consisting of reactive powder metals and alloys by consolidation using at least one method selected from low-temperature loose sintering in vacuum, high-temperature loose sintering in vacuum, low-pressure sintering in an inert gas, cold pressing, direct powder rolling, isostatic or die pressing, and other means of room temperature and warm temperature consolidation, and / or combination thereof, to provide the density not less than 25% from the theoretical density of said reactive alloy; (b) hot consolidating by hot pressing said preform, hot rolling, hot isostatic pressing, or hot extrusion to obtain the density of 98-100% from the theoretical density of said reactive alloy; (c) additional sintering and / or annealing at the temperature being at least 900° C. to decrease the residual porosity, control the microstructure, and improve the mechanical properties, especially ductility and / or plasticity of the resulting metal sheets or layered composites. The hot pressing is carried out at the temperature ranging 950-1700° C., preferably at 1250-1450° C., and at pressure ranging 50-350 kg / cm2. The HIP is carried out at the temperature ranging 1250-1350° C. and at pressure ranging 15000-40000 psi. The layered composite preform is manufactured by individual loose sintering, one layer of the composite at a time, and assembling them in the desired order. The composite consists of layers of titanium and / or titanium hydride, Ti-6Al-4V alloy, α-titanium aluminide alloy, β-titanium aluminide alloy, and γ-titanium aluminide alloy in any combinations.

A part made of a composite material containing carbon, having an open internal residual porosity is protected against oxidation by performing at least one stage in which an impregnating composition is applied, said impregnating composition containing at least one metal phosphate and titanium diboride. Efficient protection against oxidation is thus obtained at temperatures of more than 1000 DEG C, also in the presence of a carbon oxidation catalyst and in a damp medium.

Systems and methods for the fabrication of prepregs possessing enhanced ability for the removal of gases from within prepregs and prepreg layups prior to and / or during at least a portion of consolidation and cure process to form composite structures are disclosed. In certain embodiments, perforations of selected configurations may be introduced into the prepregs prior to, during, and after layup. The perforations provide routes for gases trapped within and between the perforated prepregs and prepreg lay-ups to escape during consolidation and cure process, reducing the residual porosity within the resulting composite. For example, composites having residual porosities less than 10 vol. %, on the basis of the volume of the composite, may be achieved in this manner.

A sintered gearwheel is described having teeth (1) which, in the flank and root region (2, 3), comprise a compacted surface layer (7, 8, 9) which is continuous in the transition portion (4) between the flank and root region (2, 3) and has a residual porosity of less than 10%. In order to increase the load-bearing capacity it is proposed that the compacted surface layer (9) is formed with a lower thickness in the transitional portion (4) between the flank and root region (2, 3) than in the adjacent flank and root regions (2, 3).

An opaque zone in the polycrystalline (PCA) discharge vessel of a high intensity discharge lamp may be made by creating residual pores in predetermined regions of the final-sintered discharge vessel. The control over the placement of the opaque zone is achieved by forming a carbonaceous residue in a specific region of the discharge vessel prior to final sintering. During sintering, the carbonaceous material causes residual porosity in the sintered PCA. The higher emissivity of the opaque PCA provides localized cooling in order to provide more control over the condensate behavior in the discharge vessel.

The invention relates to a compact dispersion-strengthened copper-base composite material and a preparation method thereof. The compact dispersion-strengthened copper-base composite material is composed of a copper alloy base and Al2O3 particles which are uniformly dispersed in the copper alloy base. Composite metals are added into the copper-alumina master alloy, and a vacuum induction hot-pressing furnace or low-pressure isostatic sintering furnace is adopted for sintering to maximally eliminate the residual porosity and defects in the alloy, so that the sintered billet basically reaches the theoretical density. The prepared dispersion-strengthened copper product has the advantages of high electric conductivity, high softening temperature resistance and high compactness, and can achieve more than 99.5% of theoretical density.

The invention provides a preparation method for a metal-based ceramic composite material grinding roller of a vertical grinding machine. A grinding roller base body is sleeved with a roller sleeve which is composed of a high-chromium alloy lining plate and a ceramic lining plate made of a metal-based ceramic enhanced material, wherein the metal-based ceramic enhanced material is composed of 10%-40% of corundum and 60%-90% of iron powder; the high-chromium alloy lining plate and the ceramic lining plate, and the roller sleeve and the grinding roller base body are solidified into a whole body by pouring steel liquid; the preparation method of the grinding roller comprises the following steps: when the corundum and the iron powder are mixed and combusted until the iron powder is completely smelted, the mixture of the corundum and the iron powder is put into a mould for preparing the ceramic lining plate; the ceramic lining plate is placed in a groove in the high-chromium alloy lining plate and the steel liquid is poured to prepare the roller sleeve; the grinding roller base body is sleeved with the roller sleeve and the steel liquid is poured so that the roller sleeve and the grinding roller base body are solidified into the whole body. According to the preparation method, the steel liquid can be immersed into ceramic grains in the ceramic lining plate and covers the ceramic grains so that a ceramic phase and a metal phase are uniformly distributed; the residual porosity after baking is reduced and the wear resistance is high.

The invention relates to a method for welding a sintered shaped body (1), which has a residual porosity and which is melted in the area of a subsequent weld seam (3) by a laser beam (4). In order to obtain tight weld seams, the invention provides that, during the melting of the shaped body (1), the atmospheric oxygen from the pores of the shaped body (1) is at least largely bound in the weld seam area by means of a deoxidizing agent, and is embedded in the weld seam (3) in the form of finely dispersed oxides.

The present invention relates to a method for preparing a fully ceramic capsulated nuclear fuel material containing three-layer-structured isotropic nuclear fuel particles coated with a ceramic having a composition which has a higher shrinkage than a matrix in order to prevent cracking of ceramic nuclear fuel, wherein the three-layer-structured nuclear fuel particles before coating is included in the range of between 5 and 40 fractions by volume based on after sintering. More specifically, the present invention provides a composition for preparing a fully ceramic capsulated nuclear fuel containing three-layer-structured isotropic particles coated with the substance which includes, as a main ingredient, a silicon carbine derived from a precursor of the silicon carbide wherein a condition of ΔLc>ΔLm at normal pressure sintering is created, where the sintering shrinkage of the coating layer of the three-layer-structured isotropic nuclear fuel particles is ΔLc and the sintering shrinkage of the silicon carbide matrix is ΔLm; material produced therefrom; and a method for manufacturing the material. The residual porosity of the fully ceramic capsulated nuclear fuel material is 4% or less.