39results about How to "Avoid cracking tendencies" patented technology

The invention provides a method for preparing a continuous alumina-based ceramic fiber, which relates to an alumina-based ceramic fiber, in particular to a method for preparing a continuous alumina-based ceramic fiber which takes alumina as a main component and adds a second component as a crystalling phase inhibitor. The invention provides a method for preparing the continuous alumina-based ceramic fiber, which is simple in technique and low in cost. The method comprises the steps: preparing alumina sol; preparing silicon dioxide sol; mixing the alumina sol and the silicon dioxide sol to obtain biphase sol, and adding a spinning addition agent into the biphase sol; condensing the biphase sol added with the addition agent and spinning by a dry method to obtain the gel fiber; pyrolyzing the gel fiber to obtain the ceramic fiber; and sintering the ceramic fiber to obtain the continuous alumina-based ceramic fiber.

The invention discloses an electromagnetic thermal effect weld metal crack arrest and welded structure strengthening device, which comprises a boost pressure rectification unit, a high pressure energy storage unit and a pulse discharge unit, wherein two outputted terminals of pulse discharge unit are connected with components of the welded structure through fasteners. The welded structure weld metal cracking and structure strengthening are realized through adopting the method of instant high pressure pulse discharge, the surface of an electrode is tightly applied with the surface of welded structure and a crossing type positive electrode and negative electrode is formed towards a weld seam when the electrode is fixed on the components of the welded structure through a fastener, and basic parameters such as discharge voltage and discharge time and the like are analyzed and determined through applying numerical modeling or theoretical analysis. The electromagnetic thermal effect weld metal micro-crack arrest and strengthening prevents the development of the micro-crack, realizes the ultra-fining of structures around the weld seam, removes residual stress in the weld seam, thereby achieving the purpose of strengthening and toughening of the welded structure. The invention simultaneously does not change the structure and property of a body without crack welded structure, and has the advantages of simple application method, instant finish, low cost and on-line strengthening repair and the like.

The invention discloses an aluminum alloy variable section extruded profile for spaceflight and a preparation method of the aluminum alloy variable section extruded profile. The profile consists of the following elements of, in percentage by weight, 5.0%-6.0% of Zn, 1.0%-2.0% of Cu, 0.04%-0.1% of Mn, 2.0%-3.0% of Mg, 0.15%-0.25% of Cr, 0.35%-0.42% of Fe, less than or equal to 0.25% of Si, and thebalance Al. During preparation, a finished product is obtained after being subjected to smelting, purifying, standing, casting, homogenizing treatment, ingot heating, extrusion, pre-finishing, solution treatment, straightening finishing, deep machining, aging treatment and fine adjustment treatment. According to the method, by setting specific alloy composition and the preparation process, the aluminum alloy variable section extruded profile formed by once is obtained, the strength, fatigue resistance, corrosion resistance and stress corrosion resistance of the aluminum alloy profile are greatly improved, comprehensive performance requirements of a carrier rocket launcher on the variable section aluminum alloy profile can be met, the bottleneck of extrusion forming of the variable sectionprofile at present is broken, various indexes of the aluminum alloy profile are ensured to meet standards and use requirements, and material guarantee is provided for research of new carrier rockets in China.

The invention relates to a casting method for inhibiting bottom crack of an ingot. The numerical values of casting speed and cooling water flow in the initial stage of casting are both 1/2-2/3 of those of casting speed and cooling water flow in the stable stage, when the length of the ingot achieves 20-100mm, the cooling water flow is kept still, the casting speed gradually reduces to zero within1-10s, after the casting machine stops running for 1-60s, the casting process is restarted, the numerical values of casting speed and cooling water flow are gradually restored to the initial preset values, the casting speed gradually reduces to zero after the initial stage, the stable stage and the ending stage of the casting process, and the casting machine suspends once in the midway during thewhole casting process. The technical scheme can effectively reduce overall inner-stress value of the ingot, achieve the aim of inhibiting crack and improve casting success ratio.

The invention relates to the field of steel for knitting machinery, in particular to high-wear-resistant steel for a knitting needle and a manufacturing method of the high-wear-resistant steel for the knitting needle. The high-wear-resistant steel comprises the following ingredients (weight percentage): C 0.8-1.2%, Si 0.1-0.4%, Mn 0.4-0.6%, Nb 0.1-0.15%, V 0.1-0.15%, Ni 0.1-0.3%, Cr 0.1-0.3%, and Fe and other unavoidable impurities in balance. A steel ingot casted after being subjected to smelting in an induction furnace is arranged in an electroslag remelting device as a consumable electrode for electroslag remelting, and then liquid metal drops in a water-cooling crystallizer at the bottom through a slag layer of a slag pool so as to be re-solidified to a steel ingot. After being heated a temperature range of 1000-1030 DEG C and kept for 3-5 hours, the re-solidified steel ingot is sequentially forged, bent, flattened, milled and subjected to thermal treatment to obtain cold working die steel with high combination of strength and toughness , high hardness, high wear resistance and the like.

The invention relates to a composite brazing filler metal layer for brazing ceramic and alloy, and belongs to the field of brazing filler metal. The brazing filler metal comprises a double-layer CuTiZrNi amorphous brazing filler metal and a foam Cu intermediate layer, and the foam Cu intermediate layer is filled between the double-layer CuTiZrNi amorphous brazing filler metal, and the atomic percentage of the CuTiZrNi brazing filler metal is Cu: 41.83, Ti: 30.21, Zr:19.76 and Ni:8.19. A foam Cu intermediate layer is added into the CuTiZrNi amorphous brazing filler metal, the brazing temperature is kept at 910 DEG c for 20 minutes, plastic deformation is generated between the brazing filler metal and the foam Cu intermediate layer,and the brazing filler metal and the foam cu intermediate layer are in close contact with each other, the surface of the base material is wetted, so that part of the base material is also dissolved in the molten brazing filler metal, a staggered structure isgenerated, so that the mechanical property of the ceramic and alloy connectivity is improved, the bonding strength of the interface is improved, the stress is effectively released, the cracking tendency is inhibited, so that the weld joint has good joint performance, and the negative influence of the hardening and the ductility of the braze welding head on the bonding strength is avoided;

The invention relates to the field of steel for knitting machinery and specifically relates to a high wear resistance steel for knitting needle and a manufacture method thereof. The high wear resistance steel for knitting needle comprises, by weight, 0.8-1.2% of C, 0.1-0.4% of Si, 0.4-0.6% of Mn, 0.1-0.15% of Nb, 0.1-0.15% of V, 0.1-0.3% of Ni, 0.1-0.3% of Cr and the balance of Fe and inevitable impurities. A steel ingot casted after melting in an induction furnace is employed as a consumable electrode and placed in an electroslag remelting apparatus for electroslag remelting; liquid metal passes through a slag layer of a slag bath, falls to a water cooling crystallizer below and solidifies into a steel ingot again; the steel ingot is heated to 1000-1030 DEG C, insulated for 3-5 h and treated with forging, turning, flattening and milling and heat treatment, so as to obtain a cold working die steel with characteristics of high strength and toughness cooperation, high hardness and high wear resistance, etc.

The invention discloses an oil removal and heavy metal removal modified walnut shell filter material and a preparation method thereof; the surface of the oil removal and heavy metal removal modified walnut shell filter material is provided with an oxidized graphene coating. The preparation method of the filter material includes the steps that walnut shell powder and oxidized graphene powder are added into a V-shaped mixer simultaneously to be stirred and mixed uniformly, then a cross-linking agent and deionized water are added, cross linking is conducted at the temperature of 50-80 DEG C for 3-3.5 hours, after the liquid phase is filtered out, absolute ethyl alcohol is washed to be neutral, drying is conducted for 1-3 hours at the temperature of 100-140 DEG C, finally a vibration screen is utilized to screen out the filter material with the particle size meeting the requirement, and a finished product is obtained. By means of the filter material, grease and heavy metal in sewage water can be removed simultaneously, the sewage treatment process is greatly simplified, sewage treatment cost is lowered, sewage treatment efficiency is high, the filter material is high in hardness, resistant to wear, good in pressing resistance, not prone to caking, large in toughness, easy to regenerate, long in replacement cycle and low in cost.

The invention discloses a vacuum brazing connection method for C/C radiating fins and Ti tubes. The method comprises the following specific process steps: grinding and polishing a Ti pipe to remove an oxide film, and performing vacuum drying for later use after ultrasonic cleaning; tiZrNiCu alloy powder and TiC powder with the mass percent being 3%-5% are mixed, then alcohol is added for ball milling for 15-18 h, the powder is dried and sieved after ball milling, then an oily binder with the mass percent being 8%-10% is added into sieved powder, the mixture is stirred into paste brazing filler metal, then the portion between the connecting surfaces of the C/C cooling fins and the Ti pipe is filled with the paste brazing filler metal, assembling is conducted, and the C/C cooling fins and the Ti pipe are assembled. And the assembly part is clamped by a graphite clamp and then placed in a vacuum furnace, the temperature is increased to 920 DEG C at the speed of 4-7 DEG C/min under the vacuum degree not lower than 1 * 10 <-3 > Pa, heat preservation is conducted for 10-20 min, and finally connection is completed after the furnace is cooled to the room temperature. The connecting method is simple in process, safe, free of pollution, low in cost and high in reliability, and the problems that in the welding process, due to large residual stress, a connecting piece cracks, and wettability between base metal is insufficient are effectively solved.

The invention relates to a heat-resistant sphere which is prepared from the following components in percentage by weight: 3.00-4.20% of C, 1.8-3.0% of Si, 0.2-1.2 of Mn, 2.0-4.0% of Ni, 0.3-1.0% of Mo, less than or equal to 0.07% of P, less than or equal to 0.02% of S and the balance of Fe. According to the heat-resistant sphere provided by the invention, the fatigue resistance of the material is guaranteed by adding Ni and Mo elements; and moreover, the cold cracking tendency is reduced, the safety coefficient is improved, and the service life is prolonged. The preparation process is further improved, for example, the content of S is strictly controlled, and S is removed in a ladle by using industrial sodium carbonate; a metal-stream inoculation treatment method is adopted; a unique high-medium annealing treatment process and the like are adopted, and the tensile strength, yield strength, ductility and hardness HS of the prepared heat-resistant sphere are greatly improved.