120results about How to "Good thermal crack resistance" patented technology

The invention discloses a cast magnesium alloy of low linear shrinkage, which belongs to the field of magnesium alloys. The magnesium alloy consists of Mg, Al, Zn, Mn, rare earth, Nb, Li and M element, wherein the materials have the following weight percentage composition: 1.5-25 percent of Al, 0.1-3.5 percent of Zn, 0.1-2.2 percent of Mn, 0.0002-16 percent of rare earth, 0.0002-4 percent of Nb, 0.0002-9 percent of Li, 0.0002-2 percent of M element and the balance Mg; and the M element is at least one of Zr, Ti, Sr, Ca, C and B. According to the heat-resistant magnesium alloy, the rare earth element and the Nb element are added into the magnesium alloy, so that the structure of beta phase is changed; the Zr element and the M element are added to refine crystal grains; due to combined action of the elements, latent heat of crystallization during alloy solidification is changed; and the magnesium alloy which has superior mold-filling capacity, low shrinkage, superior mechanical property and good machinability, fluidity and die-cast performance and is suitable for casting is obtained.

The invention relates to the technical field of powder metallurgy and particularly relates to a ceramic part and a production method thereof. The production method comprises (1) mixing granulation: putting ceramic powder into a mixer, heating the ceramic powder, adding a binder into the ceramic powder, carrying out mixing, and carrying out granulation through an extruder to obtain feed, (2) injection molding: placing the feed in an injection molding machine and carrying out injection molding to obtain an injected blank, (3) degreasing: placing the injected blank into an air furnace, carrying out hot degreasing, carrying out heating pre-sintering, carrying out furnace cooling and taking out a blank, and (4) sintering: putting the blank in a sintering furnace, carrying out sintering, and carrying out grinding and polishing to obtain a ceramic part. Through powder injection molding process and final degreasing and high temperature sintering, a fine ceramic part having a complex shape is obtained, the product has high compactness and good uniformity and is obtained by one step molding, the operation and control are simple, product quality is stable, production efficiency is high, a production cost is low and large-scale industrial production is realized.

The present invention discloses a hot rolling roller for rolling a nonferrous metal, and a manufacturing method thereof. Chemical components of the roller comprise, by weight, 0.50-0.80% of C, 0.30-1.20% of Si, 0.20-1.00% of Mn, less than or equal to 0.025% of P, less than or equal to 0.020% of S, 4.50-6.00% of Cr, 0.20-0.80% of Ni, 0.20-1.00% of Mo, 0.10-0.50% of V, and the balance of Fe and unavoidable impurities. The manufacturing method of the roller comprises the following process steps: a, refining a steel ingot; b, forging a roller blank; c, carrying out quenching and tempering, and carrying out mechanical processing; d, carrying out a quenching heat treatment; and e, carrying out a tempering treatment. The hot rolling roller has characteristics of high wear resistance, good thermal cracking resistance and good electrochemical corrosion resistance, and a service life of the hot rolling roller can be increased by more than 50% compared with the ordinary Cr3 roller.

The invention discloses fiber enhanced silicon carbide porous ceramic which is composed of the following components in part by weight: 1 part of a ceramic binder, 1-3 parts of mullite fiber pulp, 8 parts of silicon carbide particles with an average particle size being about 230microns, and 1 part of a pore-forming agent. The preparation method is implemented through the steps that firstly, homogeneous mullite fiber pulp is prepared, so that when the mullite fiber pulp is mixed with a binder and silicon carbide particles with large particle sizes, mullite fibers can be uniformly dispersed but not agglomerated, thereby achieving a good toughening effect in a ceramic matrix. The invention further discloses an application of the fiber enhanced silicon carbide porous ceramic in the aspects of preparing silicon carbide porous ceramics and improving the toughness of silicon carbide porous ceramics.

The invention discloses a preparation technique of a continuous casting crystallizer copper plate surface cermet coating, which comprises the following steps: copper plate surface oil removal, copper plate surface sandblasting, coating preparation and hot spraying subsequent treatment, wherein the hot spraying subsequent treatment is vacuum heat treatment or hole sealing treatment. The preparation technique of the technical scheme is simple to operate, and has the advantages of fewer steps and high efficiency. After being subjected to vacuum heat treatment or hole sealing treatment, the cermet coating has the advantages of high microhardness, small internal stress, favorable wear resistance, favorable thermal crack resistance, high bonding strength, favorable bonding property and low thermal conductivity, can lower the thermal crack of the crystallizer copper plate in the high-temperature region, can effectively decelerate the heat conduction inside crystallizer (especially the meniscus surface), and can be widely used in continuous casting of a medium/low-speed continuous caster.

The invention discloses a hard aluminum alloy for metal die casting of a precision electronic product structural member. The hard aluminum alloy is prepared by antigravity metal die casting and natural ageing heat treatment. The hard aluminum alloy comprises, by mass, 21-30% of zinc, 5.7-7.2% of silicon, 2.0-2.4% of copper, 0.17-0.35% of manganese, 0.2-0.6% of trace alloy element and the balance aluminum and unavoidable impurities with iron content of 0.27% or less. The invention also discloses a preparation method of the hard aluminum alloy. The hard aluminum alloy can be prepared by high precision die casting, has high strength, can be subjected to high quality surface treatment, can be used for production of a high precision structural member of small, thin and light electronic products, and is suitable for large parts of spaceflight and aviation, automobiles, high-speed railway, steamships and yachts and daily hardware products.

The invention discloses a copper-free friction material and a brake pad. The copper-free friction material comprises the following raw materials by weight: 30-40 parts of steel fiber, 5-15 parts of modified phenolic resin, 5-10 parts of nitrile butadiene rubber, 10-15 parts of styrene butadiene rubber, 10-15 parts of graphite, 3-4 parts of molybdenum disulfide, 5-10 parts of cryolite, 5-8 parts of barium sulfate, 1-5 parts of aramid fiber, 1-5 parts of heavy calcium carbonate, 1-5 parts of heavy magnesium oxide, 1-3 parts of aramid fiber, and 3-4 parts of silicon carbide. The brake pad made of the copper-free friction material provided by the invention has good hot cracking resistance and wear resistance, and low wear rate, thereby prolonging the service life. And reasonable control of the friction material composition proportion can ensure no abnormal wear to a brake disc.

The invention discloses a hot roll for rolling aluminium products and a manufacturing method thereof. The hot roll is prepared from the following chemical constituents in percentage by weight: 0.50-0.80% of C, 0.20-1.50% of Si, 0.20-1.00% of Mn, no more than 0.025% of P, no more than 0.025% of S, 4.50-6.00% of Cr, 0.50-2.00% of Mo, 0.10-1.00% of V and the balance of Fe and inevitable impurities. The manufacturing method for the hot roll for rolling aluminium products includes the technological steps of steel ingot refining, roll blank forging, hardening and tempering as well as machining, quenching thermal treatment, tempering and the like. The hot roll for rolling aluminium products, which is provided by the invention, has high wearing resistance, excellent hot cracking resistance and electrochemical corrosion resistance, and the service life of the hot roll is prolonged by 50% above in comparison with that of a common hot roll made of Cr3 material.

The invention discloses an alloy structural steel material for brake discs of high-speed motor train unit vehicles, which belongs to the technical field of materials for brake discs. The alloy structural steel material comprises the following chemical components in percentage by weight: 0.26 to 0.30 percent of carbon, 0.8 to 1.0 percent of silicon, 0.7 to 0.9 percent of manganese, 0.9 to 1.0 percent of chromium, 0.6 to 0.8 percent of nickel, 0.2 to 0.4 percent of molybdenum, 0.01 to 0.02 percent of tungsten, 0.09 to 1.0 percent of vanadium, 0.07 to 0.08 percent of niobium, less than 0.2 percent of phosphorus, less than 0.1 percent of sulfur, and the balance of iron. The alloy structural steel material solves the problem of thermal crack damage of the conventional brake disc friction surface due to poor heat conductivity, and meanwhile, the brake disc material has enough thermal fatigue performance, high and stable friction coefficient, good abrasion resistance and thermal cracking resistance and light weight.

A graphite-containing, heat-resistant cast iron for exhaust equipment members used at temperatures exceeding 800° C., comprising 3.5-5.6% of Si and 1.2-15% of W on a weight basis, and having intermediate layers, in which W and Si are concentrated, in the boundaries of graphite particles and a matrix. An exhaust equipment member formed by this heat-resistant cast iron has an A_C transformation point is 840° C. or higher when measured from 30° C. at a temperature-elevating speed of 3° C./minute, and a thermal cracking life of 780 cycles or more in a thermal fatigue test, in which heating and cooling are conducted under the conditions of an upper-limit temperature of 840° C., a temperature amplitude of 690° C. and a constraint ratio of 0.25.

The invention relates to the technical field of rollers, and provides a high-nitrogen high-speed steel centrifugal composite roller. The high-nitrogen high-speed steel centrifugal composite roller comprises an outer layer and a core part. The outer layer is made of high-nitrogen high-speed steel and is prepared from the following components in percentage by weight: 0.8-1.8% of C, 0.3-1.0% of Si, 0.4-1.0% of Mn, less than or equal to 0.030% of P, less than or equal to 0.025% of S, 5.0-15.0% of Cr, 0.5-4.0% of Mo, less than or equal to 2.0% of Ni, less than or equal to 5.0% of V, less than or equal to 3.0% of Nb, less than or equal to 5.0% of W, 60-300ppm of [N] and the balance of Fe. The core part is made of high-strength nodular cast iron and comprises the following components in percentage by weight: 2.5-3.5% of C, 2.0-3.0% of Si 2, 0.3-0.8% of Mn, less than or equal to 0.10% of P, less than or equal to 0.03% of S, less than or equal to 0.5% of Mo, less than or equal to 0.5% of Cr, more than or equal to 0.04% of Mg and the balance of Fe. Through the technical scheme, the problems of poor toughness, wear resistance and thermal fatigue crack resistance of the outer layer in the prior art are solved.