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Spanish Descartes green and environmental friendly welding materials

flux products such as copper and copper alloy solder paste, welding glue and welding oil originated in Europe are green and environmental friendly, which means safety, convenience and practicality to installation technicians

copper and copper alloys are widely used in electrical, chemical, mechanical, power, transportation and other industrial sectors because of their good conductivity, heat conduction, corrosion resistance and formability, but copper and copper alloys are also restricted in their wider or more convenient applications because of their poor weldability

the main problems of copper and copper alloys in melting welding are:

poor penetration and easy deformation. The high thermal conductivity of copper and copper alloys makes it difficult to heat the welding area to the required temperature. Therefore, high-power heat sources should be used during melting welding, and preheating should be carried out before welding. In addition, the expansion coefficient of copper and copper alloy is relatively large, and the shrinkage rate is also large when changing from liquid to solid. If there are no anti deformation measures, the weldment will be seriously deformed after welding

it is easy to oxidize, and the mechanical properties of welded joints are low, resulting in unpredictable problems. Copper is not easy to oxidize at room temperature, but when the temperature rises to more than 300 ℃, its oxidation capacity will quickly increase. When the temperature is close to the melting point, its oxidation ability is the strongest, forming cuprous oxide. When the weld metal crystallizes, cuprous oxide and copper will form low melting point eutectic, which is distributed on the crystal surface of copper, greatly reducing the mechanical properties of the welded joint, and its strength can be reduced to only 1//3 of the base metal

easy to produce pores. Blowholes are a major problem in the welding of copper and copper alloys. On the one hand, the high thermal conductivity of copper makes the crystallization and solidification process of copper welds particularly fast. Therefore, the system must be connected well according to the contents of the manual for the first time. It is understood that hydrogen in the weld is not easy to float and escape, so blowholes are formed in the weld; On the other hand, the hydrogen in the molten pool is added with no more than 20% of the regenerated composite film material or carbon monoxide reacts with cuprous oxide to generate water vapor and carbon dioxide, which are insoluble in liquid copper. If they fail to escape completely during solidification, pores are formed

easy to crack. When welding copper and copper alloys, cracks occur in the weld and near weld area, of which the most common is hot cracks. The tendency of hot cracks is related to two factors: one is the influence of impurities in the weld, and the other is the stress produced in the welding process

in addition to the common problems of melting and welding of copper and copper alloys mentioned above, for example, brass can also form pores in the weld due to the evaporation of zinc during melting and welding, and bronze also has problems such as the formation of tin oxide during welding, the formation of hard and brittle inclusions in the weld metal, and the reduction of the corrosion resistance of the weld

in addition, the hardness of copper becomes lower at high temperature, and other characteristics will also disappear. Therefore, brazing is generally used for copper and copper alloys (the temperature of the solder is lower than that of the base metal, the solder melts and the base metal does not melt during welding, and the connection between parts is realized by wetting and spreading the liquid solder on the surface of the base metal, dissolving and diffusing with the base metal, wetting in the gap of the base metal, capillary flow, caulking and dissolving and diffusing with the base metal, and the two are physically combined. It is customary to take 450 degrees as the boundary between brazing and brazing), And usually for copper pipes and copper materials with working environment temperature less than 100 ℃, diameter less than 50 mm and not very long, we prefer soft soldering

compared with fusion welding and pressure welding, brazing has the following advantages:

brazing heating temperature is low, which has little effect on the microstructure and properties of base metal

the brazed joint is flat and smooth with beautiful appearance

the deformation of the weldment is small, especially when the brazing method of uniform heating (such as brazing in the furnace) is adopted, the deformation of the weldment can be reduced to a minimum, which is easy to ensure the dimensional accuracy of the weldment

some brazing methods can be welded into dozens or hundreds of brazing joints at a time, with high productivity

can realize the connection of dissimilar metals or alloys, metals and nonmetals

it can be seen from the above that brazing is made by welding objects with molten alloy electrode. In order to achieve a satisfactory welded joint, it is necessary to wet the base metal after the alloy electrode liquefies and flows (that is, completely fill the weld), and an important factor affecting the wettability of solder is the state of the base metal surface and produce vibration and noise:. The adhesion of liquid alloy electrode depends on the cleaning between the metal surface and the molten alloy electrode covering it, that is, if there are any other substances in the metal bottom layer and the added alloy, the alloy cannot be fully extended, the tightness of the connection will be broken, and the welding will have problems, which is the common reason for the failure of brazing welding

in the traditional welding process, the surface of the weldment must be cleaned before brazing of copper and copper alloy. There are two methods of cleaning: physical and chemical. The physical method is to use a file, emery cloth or grinding wheel to remove the rust and oxide on the surface of the weldment, and the chemical method is to soak the weldment in hot corrosive solutions such as sodium hydroxide and sodium carbonate. The cleaned welded joint shall be brazed as soon as possible to avoid oxidation of the weldment at room temperature

even if the impurities, oxides or residues on the metal surface are removed, we still cannot heat the metal or alloy, because we must protect the metal from the newly formed oxides during the heating process. Products that prevent the formation of oxides during heating can ensure the cleanness of the surface during welding. This product is "descaling agent" or "flux". At present, the flux used in brazing copper alloys in China is flux 102 or gas flux 301 (borax, boric acid and fluoride are the main elements). These two cosolvents are highly corrosive and toxic substances, which stimulate eyes, skin and digestive tract. If inhaled, they are harmful to health and can only be used in a ventilated environment. Clean the welding joint in time after welding, otherwise the residual flux will still corrode the weldment

at present, consumers have higher and higher requirements for environmental protection of products. It is reported that the EU will officially implement the RoHS Directive on environmental protection from July 1, 2006, that is, prohibit or restrict the use of six harmful substances such as lead, mercury, cadmium, hexavalent chromium, polybrominated diphenyl ether and polybrominated biphenyls in newly launched electrical and electronic equipment products. Once the EU ROHS directive is implemented, About 12billion US dollars of mechanical and electrical products exported by China to the EU may be rejected. The prohibition of the use of lead in products in the directive ends the traditional tin lead welding process in the processing of electronic products, and 102 brazing flux and 301 copper gas welding flux will face the same problem in the future

Spanish Descartes 93 company has accumulated 15 years of experience in the field of pipeline, heating and air conditioning equipment manufacturing. Based on the needs of users, the variety and performance of products are constantly innovating. Copper and copper alloy solder paste, welding glue, welding oil and other flux products brought from Europe are green and environmental friendly, which means safety, convenience and practicality to installation technicians. Products adopt a variety of national and international standards, including ISO, force, water coil and other standards. Ecoliquid (green environment-friendly welding oil), ecogel (green environment-friendly welding glue) and ecopaste (green environment-friendly solder paste) are liquid, colloidal and paste products in dijiabu green environment-friendly flux series respectively. They do not contain zinc chloride, which is non irritating, non-toxic, non corrosive and non acidic. When using:

apply welding oil directly to the welding part of the weldment without cleaning the brazed joint in advance. It is not necessary to add water to mix with 301 welding powder

the pH value of this product is neutral, so it has no irritation to the skin. You can use either a built-in brush or fingers, and it will not wipe off the edge like 301 welding powder

heat slightly until the flux is activated, add solder, and the flux will disperse due to capillary action, with good fluidity

remove excess welding oil after welding. The product is non corrosive, and it doesn't matter if there is a small amount of residue

the toxicity test of this product has proved that it is not toxic when swallowed. (end)

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