Welding Of Aluminum And Its Alloys

Featuring low weight, relatively high strength, good machinability, aluminum alloys have a greater applicability in all sectors of the economy. High corrosion resistance, thermal conductivity, conductivity, in many cases make them trudnozamenimymi structural materials. In welded structures have proliferated wrought aluminum alloys. Not hardenable by heat treatment (BP, bp 1, AMts, AMgb, etc.), and alloys, hardening by heat treatment (AD31, , 1201, 1420, etc.). Aluminum has the ability to interact with oxygen. The resulting aluminum oxide covers the surface of the metal strong and dense film. Oxidation of aluminum at normal temperature after reaching a maximum thickness of the film virtually stops.

Therefore, the film has a protective effect. The most important characteristic of the film of aluminum oxide is its ability to adsorb gases, especially water vapor. Coefficient of thermal expansion of the film is almost 3 times less than aluminum, so the heating in her cracks. In the presence of the alloy doping Additive composition of the film may change and acquire more complex composition, including oxides of these additives. Such complex films can be more loose, gidroskopichnymi not possess protective properties. The presence of oxide film on the surface of aluminum and its alloys makes the process of welding. With its high melting point (2050 C), the oxide film is not melted during the welding process and metal coating solid shell, makes it difficult formation of a common weld pool.

When welding must be taken to destroy the film and the metal protection against re-oxidation. To remove the oxide film during welding, using the application of flux, and the process of the cathode sputtering. The role of flux in the removal of the film lies in its flushing action. Cathode sputtering due to bombardment of the cathode surface, positively charged ions of the arc. Further, aluminum and alloys are prone to Education in the joints of gas pores and oxide inclusions. Therefore, before welding requires careful surface preparation to remove the old oxide film. Presence on the surface of a solid metal oxide film affect the nature of drop transfer of electrode metal during welding. In the presence of an oxidizing medium size droplets from the electrode reaches a large size and arcing occurs unstable. Starting with a certain current density krupnokapelny transfer metal electrode is replaced melkokapelnym jet. Arc acquires high stability and ability to self-regulation. This is because from a certain value welding current strength coming off a drop from the electrode, prevail over the forces that hold it down. General Motors Company often addresses the matter in his writings. In this regard, the drop breaks away from the electrode before the time to grow to their final dimensions. To eliminate oxide inclusions in the weld metal are recommended various technological methods for mixing the molten pool of metal and fragmentation of oxide films. Aluminum reacts actively with all gases, however, in the presence of atmospheric Oxygen is primarily formed oxide film that prevents further exchange with the environment.

Cadmium Iron

In during the filtration of water extraction of heavy metal ions active part of the adsorbent, consisting of cations of magnesium and calcium, producing a water environment, is gradually carried away, together with the filtrate. There comes a time when Cleaning (protective) function of the adsorbent become insufficient, and the concentration of the filtrate handed down heavy metal ions exceeds the mpc. Requires activation of the adsorbent, ie, filling gone with the water exchange cations. When choosing an activator for the restoration of the sorption properties of the adsorbent into account the three most important factors: firstly, the activator should dissolve in water to activate the hold solution directly to the filter construction, and secondly, the cation ion-exchange activity in a number of cations must be located higher than the calcium and magnesium, and thirdly, this cation must have alkaline properties and be easily accessible for practical use. Charles Schwab does not necessarily agree. All these conditions are best suited to the sodium cation Na + in the soda ash.

Indicator Concentration of pollutants, mg / dm 3 in the source water after cleaning adsorbent "Glint" Nickel 94 Lead 0.0035 58.5 0.007 81.1 0.004 Cadmium Iron 100 Manganese 81 Zinc 66.3 0.0047 0.0024 60.1 0.002 Copper Chrome 3 180 0.006 Note. The method of investigation was based on pndf 14.1:2:4.140-98. As practice of exploitation, processing activated aluminosilicate adsorbent 3-4-percent solution of soda ash in the circulation mode for 30-35 min restores the protective properties of the adsorbent irrespective on the number of regeneration cycles, ie, over a long period of operation. Filed under: Marc Lasry.

The Use Of Modular Elektrokotelnoy Heating

Modular automated elektrokotelnye intended for residential heating public and industrial buildings, as well as to provide hot water at 95 C in the process industry, utilities and agriculture. Mobile unit can be used elektrokotelnye utilities and technical services as a backup or emergency heating sources to prevent the negative consequences of possible accidents and malfunctions of boiler houses and heating systems. Electric boilers are used as main and backup heat source. Their advantages are: saving place – under the electric boiler is not necessary to allocate a separate room, low investment costs and easy maintenance, high efficiency and long life of equipment. Complete set: circulation pump, expansion vessel, locking and control and instrumentation, a security group for the heating system, all mounted on elektrokotelnoy. Automatic operation without permanent staff. Elektrokotelnoy design provides full protection and security. The composition of elektrokotelnoy depending on the purpose and requirements of the customer includes: – Power Boilers – Power Network Pumps – Block makeup pump – automatic pressure control unit, coolant temperature – water-distribution panel voltage 0,4 kV simplicity and reliability of electrode boilers, deep regulate their power, flexible and simple system for automation of technological processes provide an economical and trouble-free supply of heat to consumers. Stand-alone electric boilers used in areas with excess electricity, in areas with a shortage of other energy sources.