8results about How to "Improve anti-ablation performance" patented technology

The application discloses a kind of multi-element ultra-high temperature nanocomposite ceramic matrix composites and preparation method thereof, the multi-element ultra-high temperature nanocomposite ceramic matrix composites are composed of multi-element ultra-high temperature nanocomposite ceramic and porous fiber body, wherein multi-element ultra-high temperature nanocomposite ceramic is composed of oxygen-free silicon-based ceramic and multi-element transition metal carbonitride uniformly distributed therein, and the preparation method is: at least two metal element complexes are reacted with silicon-based polymer to obtain single-source precursor polymer;Then porous fiber body is placed in single-source precursor polymer solution for multiple times of impregnation pyrolysis, and the composite material provided by the application has a nanocomposite structure, an ultra-high temperature ceramic multi-element single-phase solid solution, the type, content and ratio of metal elements can be adjusted, the ultra-high temperature ceramic in the matrix is uniformly distributed and has a nanoscale grain size, and the method can avoid damage to the fiber during preparation, thereby achieving simultaneous improvement of the mechanical properties and oxidation ablation resistance of the composite material.

This invention discloses a method for preparing high-entropy ceramic matrix composites using a reactive infiltration process, belonging to the technical field of ceramic matrix composites. The steps are as follows: at least four single-component carbides are ball-milled and mixed with a carbon source, then dispersed in a dispersion liquid to obtain a slurry; continuous fibers are woven into a preform, and an interface layer and a matrix layer are deposited to obtain a semi-dense composite material; the slurry is introduced through vacuum or pressure impregnation; and a high-entropy carbide matrix is ​​generated in situ and densified by reactive infiltration after embedding with a transition metal and its alloy. This invention solves the problems of long process cycles, high porosity, high cost, and insufficient introduction of high-entropy ceramics in existing processes, achieving rapid densification and improving the material's high-temperature stability, oxidation resistance, and ablation resistance. It is suitable for the large-scale production of thermal protection materials for hypersonic vehicles.

The invention relates to a non-expansive refractory coating and a preparation method thereof, the non-expansive refractory coating comprises a component A and a component B. The component A comprises, by mass, 15-25% of high-alumina cement, 8-12% of refractory soil, 5-10% of glass powder, 5-15% of aluminum hydroxide, 5-10% of hollow glass beads, 2-5% of silica fume, 3-5% of an ethyl cellulose composite system, and the balance modified vitrified microbeads; the component B comprises 10-20% of lithium silicate, 5-10% of an acrylic emulsion, 5-15% of a pure acrylic emulsion, 0.1-0.3% of a water reducing agent, 1-2% of a wetting agent, 1-3% of a coalescing agent and the balance of water; the modified glass beads comprise titanium dioxide composite glass beads, tetrabutyl titanate and silver. The coating has the effect of improving the fire resistance of the coating.

The application provides a gradient wave-transparent heat shield forming method, comprising the following steps: S1, preparing a preform of a heat shield; S2, configuring ceramic slurry; S3, fusing the ceramic slurry into the preform of the heat shield to form a green body of the heat shield; S4, placing the green body of the heat shield into the ceramic slurry to densify the green body of the heat shield; and S5, sealing a large port of the green body of the heat shield and performing solution infiltration on the green body of the heat shield by using polytetrafluoroethylene to form the heat shield. The heat shield prepared by the method not only has the functions of bearing and transmitting waves, but also has excellent heat insulation and heat protection functions.

The application discloses a tubular object inner wall double-glow plasma processing device, which comprises an electrode rod and a bottom disc; the bottom disc is connected with a target material tray through a first ceramic support, and the bottom disc is connected with a workpiece tray through a second ceramic support; the target material tray is provided with a target material one and a target material two, and the target material one and the target material two are in a disc shape; a hole with the same inner diameter as the workpiece is reserved on the workpiece tray, and a hollow heat preservation cover is further arranged on the workpiece tray; the workpiece is arranged at the middle position of the target material one and the target material two, and the center lines of the target material one, the target material two, the workpiece and the hollow heat preservation cover are coincident; the target material tray is connected with an electrode rod one, and the workpiece tray is connected with an electrode rod two. The application further discloses a processing method of the tubular object inner wall double-glow plasma processing device. The outer walls of the two metal target materials and the inner wall of the tubular object are at equal intervals and are located on the upper and lower sides of the tubular object, the film layer is uniform and dense, no hole and crack appear, the film layer is combined with the base body in a metallurgical way, and the service life is improved.

The application provides a quartz fiber composite surface high-temperature-resistant waterproof coating and a preparation method thereof. The coating is ytterbium silicate (YbSiO5) ceramic, is prepared by using a low-pressure plasma spraying process, has a thickness of 0.05-0.30 mm, a porosity of not more than 5%, and a thermal expansion coefficient of less than 4*10 ‑6 / K. A laser etching process is selected for a quartz fiber composite pre-spraying treatment process, X-direction and Y-direction fibers are subjected to roughening and densification treatment, and Z-direction fibers are not treated, so as to form a grid. On the one hand, the grid maintains the integrity of the fiber bundle, and on the other hand, the surface roughness is controllable, so that the coating bonding force can be greatly improved. The coating bonding strength is greater than or equal to 1 MPa, the coating has no cracking or peeling in a prepared state, and the surface has super-hydrophobic effect. The ytterbium silicate coating has good durability, can be stored stably for a long time, does not discolor or age and fall off, is resistant to 1600 DEG C ablation, and has a water immersion weight gain rate of not more than 0.02 g / (cm 2 *h) after ablation.

The application discloses a contact structure with active vacuum arc dispersing function based on internal phase change driving, which comprises a static side contact piece, a static side conductive rod fixedly connected with the static side contact piece, a dynamic side contact piece oppositely arranged with the static side contact piece, and a dynamic side conductive rod fixedly connected with the dynamic side contact piece, wherein arc dispersing devices are arranged in the static side contact piece and the dynamic side contact piece, and the two arc dispersing devices are symmetrically arranged with the radial center line of the contact structure as the symmetric axis. The arc dispersing device is a hollow sealing structure, the side close to the contact surface is a flexible metal diaphragm, the inside is filled with liquid low-boiling point working medium, and the bottom is provided with a capillary core structure made of porous sintered material. The contact structure can drive the phase change of the built-in working medium by the energy of the arc itself, generate transient mechanical pulse to make the arc root continuously move on the anode surface, thereby destroy the stable heat conduction of the arc to the local anode, inhibit the anode ablation from the source, and improve the anti-ablation ability and service life of the vacuum switch.

The invention discloses a gradient density fiber reinforced phenolic aldehyde / vermiculite composite material and a preparation method thereof, and belongs to the technical field of composite material preparation. The invention aims to solve the problems that an existing composite material homogeneous structure is difficult to consider both surface ablation resistance and internal heat insulation, a coating is easy to peel off and thermal expansion is mismatched. The composite material is prepared through the processes of gradient density preform design, phenolic aldehyde / vermiculite nano-composite impregnation, sol-gel construction of a porous structure, ceramic precursor brush coating and high-temperature cracking to form a compact ceramic layer. The carbon-based composite material which is low in density, high in specific strength, efficient in interior heat insulation and excellent in surface ablation resistance can be obtained.