6 results about "Surface diffusion" patented technology

The invention relates to a method of oxygen hardening of a Group IV metal, comprising the steps of: providing a workpiece of a Group IV metal in its final shape; oxidizing the Group IV metal in an oxidizing atmosphere at a first temperature using a gaseous oxidizing species having an upper temperature limit of up to 800°C for an oxidation duration of at least 10 minutes to provide a non-delaminated Group IV metal oxide on the surface of the workpiece, wherein the first temperature is in the range of 500°C and the upper temperature limit of the gaseous oxidizing species; diffusing oxygen from the non-delaminated Group IV metal oxide into the Group IV metal in an inert atmosphere at a second temperature in the range of 500°C to 800°C and at a partial pressure of the gaseous oxidizing species of up to 10"4mbar for a diffusion duration of at least 0.1 hour to provide a surface diffusion zone comprising oxygen in solid solution. In another aspect, the invention relates to a Group IV metal component comprising a material core having a core hardness and a surface hardness of at least the core hardness + 200 HV 0.025 The component is obtainable in the method of the invention.

The invention provides a method for predicting the permeability of a hydrate-containing sediment reservoir, and belongs to the technical field of unconventional oil and gas development. According to the method, the characteristics of pore size distribution, tortuosity and the like of a hydrate reservoir matrix are considered, a porous medium model formed by tortuosity capillary bundles is adopted to represent HBS on the basis of a fractal geometry theory, flow mechanisms such as a slippage effect, Knudsen diffusion and surface diffusion are comprehensively considered, and the influence of methane molecules adsorbed on a pipe wall on free gas molecule flow is considered; an HBS multi-scale permeability model is established, and a brand new HBS reservoir permeability model is deduced. By means of the model, the flow rule in the HBS reservoir and the change rule of the permeability can be predicted according to construction and geological parameters, and the blank of the existing theoretical technology is filled with the method.

This invention relates to the field of surface diffusion methods and discloses a surface treatment process for protecting the inner wall of a separation device. The process includes: placing the separation device in a vacuum chamber and introducing an active gas; opening the inlet gas path within a preset temperature zone to saturate and adsorb alloy atoms; constructing a constant-volume environment by simultaneously cutting off the gas path; calculating the pressure drop rate using an absolute pressure transmitter to characterize the flux consumed by atomic transfer to the crystal lattice; switching to a low-pressure permeation stage based on the flux consumed to remove the gas-phase barrier layer on the inner wall surface and drive atomic deep migration; and controlling the cooling process after the process to generate residual micro-compression stress. This invention utilizes the causal relationship between overall pressure evolution and surface diffusion dynamics to effectively suppress the precipitation of brittle intermetallic compounds, solve the mass transfer bottleneck in confined spaces, enhance the metallurgical bonding strength and homogeneity of the protective layer, and, in conjunction with pre-set stress, improve the service life of the separation device under strong erosion conditions.

This invention discloses a method for enhancing the stability of gallium nitride epitaxial growth by combining surface mobility calibration. The method involves neutralizing polarization residues on the growth layer surface through inert gas impingement and plasma activation to generate a regrowth substrate interface. Then, energy pulse-assisted control is used to alternately heat and cool the growth layer surface to obtain a regrowth layer of a predetermined thickness. The regrowth layer is then heated, and the ratio of ammonia to metal source flow rate is adjusted to generate a nitrogen-rich surface in the initial heating stage. Stress redistribution is performed in stress concentration areas to obtain a thick-layer sample. The mobility of the thick-layer sample is calibrated using a closed-loop method by comparing the mobility of a preset model with the measured surface diffusion response time to correct the timing of pulsed thermal flow period and nitrogen-rich surface formation. This invention solves the technical problems of delayed surface activity recovery, interlayer stress inhomogeneity, and rapid local dislocation propagation during the low-temperature regrowth stage, significantly improving the crystal quality and process stability of gallium nitride epitaxial layers.

The invention discloses a gallium nitride epitaxial stability enhancing method combined with surface mobility calibration, which comprises the following steps of: performing polarization residue neutralization treatment on the surface of a growth layer through inert gas impact and plasma activation to generate a regrowth substrate interface; and controlling the surface of the growth layer to be in a heating and cooling alternating state through energy pulse assistance so as to obtain a regrowth layer with a set thickness. And carrying out heating treatment on the regrowth layer, and adjusting the flow ratio of the ammonia gas to the metal source so as to generate a nitrogen-rich surface at the initial heating stage. And carrying out stress redistribution on the stress concentration area to obtain a thick-layer sample. And carrying out migration rate closed-loop calibration on the thick-layer sample by comparing the migration rate of the preset model with the actually measured surface diffusion response time so as to correct the pulse heat flow period and the generation time sequence of the nitrogen-rich surface. According to the method, the technical problems of surface activity recovery lag, uneven interlayer stress and rapid expansion of local dislocation in the low-temperature regrowth stage are solved, and the crystal quality and the process stability of the gallium nitride epitaxial layer are remarkably improved.

The invention discloses a plasma arc zone melting purification device and method, and relates to the technical field of metal purification, the plasma arc zone melting purification device comprises a plasma gun, a bearing assembly and a permanent magnet; the plasma gun is used for generating a plasma arc to form a melting zone on the metal to be purified; the permanent magnet is used for generating a static magnetic field in the melting zone; based on the characteristics of plasma arc smelting, strong current exists in melt, when a static magnetic field is applied around the melt, the current and the static magnetic field interact to generate Lorentz force, the melt generates strong convection under the action of the Lorentz force, melt convection is enhanced, impurities can be promoted to be diffused from the inside of the melt to the surface, the impurities are promoted to move to the surface at a higher speed, and therefore the impurities are prevented from entering the melt. Meanwhile, the thickness of the pasty area is reduced by enhancing convection, so that impurities are promoted to be discharged into the melting area from the pasty area, volatilization of the impurities and plasma reaction are promoted, and the purification efficiency is improved.