Steel structure is anticorrosive -- coating of metallic thermal spraying

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Metallic thermal spraying is to use the heat source of some kind of form to heat metallic spray material, made formation the particle of melt condition, these particle fall in dynamic action, sink with particular velocity shock add in matrix apparently, form the metallic coat that has particular character. Water industry steel structure the surface that waits for base material, manage through thermal spraying technical divisions, the metal that obtained corrode of anti-corrosive, wear-resisting protects coating, strengthen water industry steel structure thereby be able to bear or endure the function of corrupt, wear-resisting. More  is like the data that can be used at metallic spray zinc, stainless steel. Among them stainless steel coating has wear-resisting caustic and protective cycle to grow wait for a characteristic; Zincic coating is had not only enclothe, anti-corrosive action, more important is to have cathode to protect a function (galvanic cell principle) . They are water industry steel structure the important material of anticorrosive spray, because this receives wide application. Carry out as what north of the water austral the country moves a project, the use of water industry steel structure will mushroom, research develops a kind of new-style water industry steel structure anticorrosive technology, to dropping a project it is very cost, important to prolong project life. For this, coating of afore-mentioned two kinds of metals each some advantage is complementary, in spray of the overlay on same work matrix, serve as ground floor with zincic coating first, coating of reoccupy stainless steel serves as facing, form coating of a flight of stairs finally, in using water industry steel structure, obtained through a large number of research and experiment already economy, satisfactory anticorrosive result. One, technological process of coating of ladder of thermal spraying metal 1. Steel structure finishing: Coating of ladder of thermal spraying metal is preservative of craft like making coating of stainless steel of coarse and gush zinc, gush except rust, provide gush arenaceous power by pneumatics machine above all. In compress airy action to fall, after the quartz arenaceous  that contains what choose through the sieve edges and corners passes arenaceous bucket, glue to be in charge of arenaceous gas to mix, high speed pounds workpiece surface, eliminate the oxide such as the rust of matrix surface achieves the goal that makes matrix surface uneven. 2. Thermal spraying zinc: Basically set stock: Reduce air system, system of oxygen, acetylene, the metal enrages the equipment such as spray gun and glue canal. Its principle is: With the compression in spray gun air is impulsion, drive in actuating device below, zincic silk carries spray head, in oxygen - of acetylene blaze heat below, make melt system, borrow the pulverization that compresses air to make becomes particle and eject arrives on workpiece, form covering layer of thermal spraying zinc. Because gush is arenaceous the matrix surface after is uneven  comes loose the metallic coating after hot systole is added can firmly in workpiece surface. 3. Spray stainless steel: Main facility is the same as gush zinc, but gun of metallic gas blowout should choose middling speed gun, improve on foundation of high speed gun commonly, change partial spare parts can be used. Working principle is Alexandrine, it is zinc, stainless steel only both melting point is different, reason should adjust good oxygen - the dosage of acetylene blaze. 4. Besmear installs iron of annulus oxygen cloud, close priming paint, besmear installs AC - lacquer of face of aluminium powder of 5 chlorinated rubber. Besmear installs a method: Use method of spray of air of the manual union that brush besmear. The requirement does not have brush mark, without bubbly, without stream hang, the gush that do not have leakage, the exterior shows silver grey scene, neat, well-balanced and consistent. 2, apply April 2002, jiangsu saves steel structure of 3 rivers brake anticorrosive company enters hub of sea aqueduct seaside to establish steel structure of industry of water of the contain that make the land is anticorrosive medium applying in river of the Huaihe River of national major project this technology. 1. Select material basis designs a requirement, what zincic silk uses is the 3mm that Shanghai produces, purity is 99.

99 ％ , melting point is 420 ℃ . Surface color is bright, circularity divide evenly, the surface does not have burr, without nick, without oxidation skin. Outer packing of double deck of plastic paper, list is in good condition. The ferrite stainless steel of the 2mm that what stainless steel silk uses is Shanghai production silk. Its bases is: Chromic (Cr) content 18 ％ , nickel (Ni) 9.

0 ％ , manganese (Mn) 1.

25 ％ , melting point is 12000 ℃ . The exterior does not have nick, burr, without oxidation skin, outer packing in good condition. 2. Main technique controls (１ ) gun of metallic gas blowout: Gush zinc chooses high speed gun, spray gun mouth is 3.

2mm, air cap is used 6.

5mm, middling speed gun is chosen when gush stainless steel, spray gun mouth is 2.

2, air cap is 6.

0mm, should change worm wheel worm. (2) aerobic pressure and acetylene pressure adjust: Because zinc and stainless steel melting point are different, the oxygen when spray, acetylene dosage should be made adjust accordingly, pressure of the oxygen when gush zinc is 5 ～ 6kg/cm2, acetylene pressure is 0.

8 ～ 1.

2kg/cm2, blaze is adjusted be neuter or slant carbonization, make zincic silk is formed by blaze melt in spray gun mouth cone-shaped mist bundle eject arrives on gate; Pressure of the oxygen when gush stainless steel 6 ～ 8kg/cm2, acetylene pressure 1.

4 ～ 1.

5kg/cm2, make stainless steel silk is in spray gun mouth by oxygen, after acetylene blaze is fused, form cone-shaped particle bundle, eject arrives on steel gate. (3) control of the speed that enter silk: Because zincic silk melting point is inferior, spray gun of use high speed, the speed that enter silk is adjusted for 3 ～ 4m/min; Melting point of stainless steel silk is higher, spray gun of use middling speed, the speed that enter silk is adjusted for 2 ～ 3m/min. (4) eject distance and angle master: These two parameter affect spray quality tight ness rating directly, the course is comparative, gush zinc distance takes 15 ～ 20cm, distance of gush stainless steel takes 20 ～ 30cm; Gush zinc takes 10 ° ～ in planar place angle 30 ° , the place in a few difficulty also can put 40 ° . Gush stainless steel takes 10 ° ～ 20 ° , because angle passes,avoided so big and bring about spray layer structure inattentive, fall off phenomenal happening. 3. Coating of spray effect a flight of stairs is rock-bottom -- zincic layer grain is fine, coating is even, hole is small, close-grained sex is good, zincic layer ply achieves design requirement, because the ply of zincic layer is original in part only, adherent force is powerful, stainless steel coating enclothes his to go up, present grey black, grain is thicker, hole is large, but hard, wear-resisting, because overlay spray ply is original in part only, reason adds exert oneself it may not be a bad idea, have very good protection effect to zincic layer, use coating of iron of annulus oxygen cloud to close again, make face paint with lacquer of chlorinated rubber aluminium powder, the waterproof, performance that prevent ooze is good. Designing institute of survey of Shanghai of ministry of classics irrigation works and Jiangsu province quality detect the center is right each working procedure detects respectively, quality of coating of ladder of thermal spraying metal is good, satisfy design requirement. The nextpage3, contrast with technology of commonly used spray and experiment 1. Quality is comparative (1) gush zinc since anticorrosive company established steel structure of 3 rivers brake 1975 oneself, its steel structure gush zinc is anticorrosive craft for many times bear the palm, green jade for a long time in dam of Ge Zhou of the Yangtse River, Gansu Province sports center of state of buccal power station, Senegal tens of domestic and international major project carries on zinc of steel structure gush is anticorrosive project, a few years successful construction experience proves water is versed in the protective cycle of anticorrosive craft is zinc of steel structure gush 15 years or so, its advantage is anticorrosive function is stabilized reliably, the result is favorable, prevent osmotic strong, defect is exterior hardness poorer, wearability is insufficient, fight ruinous weak. (2) basis of spray stainless steel shows domestic and internationally about the data, the gush coating of stainless steel protects cycle to be 45 years or so, its advantage is hardness tall, wearability is good, strength is great, fight ruinous good, defect is spray anticorrosive effect is poorer, easy rustily, protect a function without cathode, the surface coarse, seepage of water is strong, enclothe close-grained sex difference, easy flake. (3) coating of ladder of thermal spraying metal this craft is the anticorrosive new technology that work up rises, but be versed in in underwater water steel structure is anticorrosive in had be notted apply extensively, to examine this is planted the anticorrosive effect of new technology, did a test: Will use gush zinc (A) board, gush stainless steel (B) board with metallic ladder coating anticorrosive (C) board 3 steel structure try board (ply of zinc of A board gush 160 μ M, ply of stainless steel of B board gush ply of zinc of gush of 160 μ M, C board ply of stainless steel of 80 μ M, gush also 80 μ M) water intrusion is medium at the same time, number is taken out after day. Result, a board face is basic invariant, with little weight light tat is hit, zincic layer suffers bump, attrition is out of shape, shift, the surface suffers attack position bare. B board surface is basic and rustily, rubiginous water in the coarse break from stainless steel surface layer oozy (did not burnish because of its, be versed in in water steel structure is anticorrosive in burnish impossibly, otherwise not only construction is difficult and cost will be multiple rise) , with little weight light tat lays stainless steel surface layer, suffer attack partial rusty spot to flake, because coating hole is large,see this technology, water penetration is strong, steel structure surface still is contacted with water and rustily, reason cannot satisfy the need with anticorrosive underwater of water industry steel structure. C board surface, in good condition be like first, without rustily, with little weight surface layer of stainless steel of light light stroke is not had wear away, flake, changeless form. This shows, coating of ladder of thermal spraying metal is preservative the result is favorable. 2. Economic benefits is comparative (watch 1) choose technology of spray stainless steel alone anticorrosive, initiative investment cost than choose gush zinc tall, coating of its stainless steel is hard, be able to bear or endure attrition, those who protect cycle to be able to be amounted to 45 years is long, but anticorrosive to project of underwater of water industry steel structure not applicable. Choose gush zinc technology alone anticorrosive, although initiative investment than more anticorrosive than choosing stainless steel and coating of ladder of thermal spraying metal craft low, but performance of zincic layer wear-resisting is poor, protection is periodic only 15 years, wait near gate waterline especially a few often get friction, erode place, cycle of zincic layer protection will be shorter, need 45 years to repeat spray 3 times above, cost of project life cycle subsequently heighten. Coating of ladder of thermal spraying metal is preservative technology, coating wear-resisting caustic, the exterior is neat, enclothe even, close-grained, protective cycle is long, anticorrosive performance is good, fight ruinous strong, do not need to organize construction 2 times, reduced cost of project life cycle significantly. The water industry steel structure that is first selection is anticorrosive technology. River of our country river is laky and numerous, coasting longer, water conservancy project is more, at the same time south the project such as water north attune also will build many water industry structure, water industry steel structure is anticorrosive face vast amount is large. Gate of water industry steel runs a course partly each in, go up in water, underwater, waterline suffers corrode with destroy degree all different, wear away degree is differ, gate gyro wheel, orbit bury get gyro wheel friction, covering layer damages extremely easily. Coating of ladder of thermal spraying metal is anticorrosive technology economy, practical, can achieve expectant result again, reason should be popularized energetically use. CNC Milling