52results about How to "Short melting range" patented technology

The invention discloses a SnBiSb low-temperature lead-free solder and a preparation method thereof, belonging to the technical field of low-temperature solder. The weight percentage composition of this lead-free solder is: Bi 32.8-56.5%, Sb 0.7-2.2%, the rest is Sn, and the weight percentage of Bi and Sb satisfies the relationship b=0.006a 2 ‑0.672a+19.61+c, wherein a is the weight percentage of Bi, b is the weight percentage of Sb, and the range of c is ‑1.85≤c≤1.85. The invention also discloses a preparation method of the lead-free solder. The solder alloy of the invention is a pereutectic or near-eutectic structure, has a low melting point, has excellent mechanical properties and reliability, and is suitable for the field of low-temperature soldering.

The invention relates to a method for refining a thiofide 2-mercaptobenzothiazole (M). The method is characterized in that an extraction method and an alkali dissolving and acid isolation method are creatively combined. The method comprises the following steps: crude thiofide M is extracted by using toluene for three times to remove resin impurities so as to obtain high-purity thiofide M; the thiofide M in the resin is purified by the alkali dissolving and acid isolation method; and the thiofideoluene is reclaimed by a distillation method. By adopting the processing, the thiofide M with high purity, high melting point and short melting period can be obtained.

The invention belongs to the technical field of polyester powder coating preparation, and in particular relates to a long-acting weather-resistant, chlorine-salt corrosion-resistant polyester powder coating and a preparation method. The main raw materials of the powder coating of the present invention are: 530-560 parts of polyester resin, 45-60 parts of TGIC, 10-15 parts of trimesic acid triglycidyl ester, 120-180 parts of titanium dioxide, and 80-120 parts of barium sulfate , 8‑12 parts of brightening agent, 7‑10 parts of leveling agent. The polyester resin used in the powder coating of the present invention has a good linear structure, which ensures excellent fluidity; the powder coating uses a larger amount of trifunctional curing agent TGIC, and is matched with triglycidyl trimesic acid with a low melting point and excellent water resistance Esters are used as low-temperature curing agents to further improve the crosslinking density and water resistance of the coating film, and finally ensure long-term weather resistance and chloride salt corrosion resistance. The final powder coating product can be used for low-temperature curing at 160°C. The coating film prepared by it has good long-term weather resistance and chlorine salt corrosion resistance, and is especially suitable for infrastructure spraying on highways such as guardrails and bridges.

A resolution method of a levocetirizine chiral intermediates belongs to the technical field of fine organic chemical engineering. The method comprises the following specific steps: adding racemic 1-[(4-chlorophenyl)benzyl]piperazine and chiral ionic liquid in a reaction container to react at 10-100 DEG C for 1-10 hours, extracting with toluene for layering, adjusting the pH value of the aqueous phase with 10wt% of sodium hydroxide solution to 11-12, extracting with toluene again, and concentrating to crystallize after the post-treatment, thus obtaining the product. The chiral ionic liquid is used as the solvent and resolving agent, the technology is easy to operate, the efficiency is high, the yield of three wastes is low, the yield of the product is more than 34%, the melting range of the product is narrow, the melting point is 94-96 DEG C, the specific rotation [alpha] D is not more than -21.5 degrees (C1, toluene), the optical purity is not less than 99.0%, and the content is not less than 99.0%. The post-treatment is convenient, the ionic liquid can be used repeatedly and the resolution method is an economical, practical, green and environmentally friendly technology.

The invention belongs to the field of solder alloys, and discloses a Sn-Bi low-silver lead-free solder alloy and a preparation method thereof. The solder alloy is composed of Sn, Bi, Ag and Cu, and the components in the solder alloy are calculated by mass percentage: Bi 40%, Ag 0.5%, 0.5%≤Cu≤1.5%, and the balance is tin. Its preparation method is as follows: after pure Sn is completely melted, add pure Bi grains to stir and smelt, then add Sn-20Ag and Sn-20Cu alloys to stir and smelt evenly, add rosin after heat preservation to remove scale residues, and cast to obtain Sn-Bi low-silver Lead-free solder alloy. The invention significantly reduces the melting range of the brazing filler metal by simultaneously adding two alloying elements, Ag and Cu, on the basis of the Sn-40Bi alloy, and greatly improves the wettability and microhardness of the brazing filler metal.

The invention discloses a reinforced nylon material for injection molding of products with high precision and complicated structure and a preparation method thereof. The invention firstly synthesizes medium-low-viscosity long-carbon-chain nylon 1012 as a base material, then adds an appropriate amount of compound processing aids, uses glass fibers for reinforcement, and utilizes a screw extruder to produce a reinforced nylon material suitable for injection molding with high precision and complex structures. The performance index of the reinforced nylon material for injection molding produced by the present invention: tensile strength>100MPa; bending strength>100MPa; notch impact>10KJ / m2; vertical and horizontal shrinkage ratio<0.1; excellent mold release performance, which can meet some sizes Demand for reinforced nylon materials for injection molding of products with high precision requirements and complex structures.

The invention discloses a composite brazing material and a brazing process, which relate to the technical field of welding. This composite brazing material can be used for brazing connection of copper-aluminum-stainless steel composite material and aluminum and stainless iron. And specifically, the composite brazing material includes composite brazing flux and aluminum-silicon solder; the composite brazing flux includes cesium fluoroaluminate with a mass ratio of 60% to 90% and a melting range of 440 to 480°C , Potassium fluoroaluminate with a mass ratio of 40% to 10%. The brazing material has a low liquidus temperature, thereby effectively reducing the brazing temperature. The solder particles are smaller and the melting range is shorter, which greatly shortens the melting time. The compound flux can effectively improve the fluidity of the solder after melting. A graphite pad is set above the lower die head of the brazing machine, which can save the copper layer turning process before welding, so that the weldment can pass 10 times of 350 ℃ dry burning test and 30 times of 300 ℃ dry burning test after welding, effectively improving the quality of the weldment Yield rate, stable and improved weldment quality.