Some knowledge of aluminum alloy die casting

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Aluminum alloy die-casting products are mainly used in electronics, automobiles, motors, household appliances and some communication industries, etc. Some high-quality aluminum alloy products with high performance, high precision and high toughness are also used in large aircraft, ships and other industries with high requirements. The main use is in some equipment parts.

The history of

The history of die casting is varied. According to relevant articles, die casting lead appeared initially. In 1822, Willam Church made a type casting machine with a daily output of 12,000 to 20,000 yuan. More than two decades later, J.J.Sturgis designed and built the first manual piston hot chamber die casting machine, which was patented in the United States. In 1885, Mergenthaler studied the previous patent and invented the printing die casting machine.

By the 1860s, it was used in the production of zinc alloy die casting parts. It was only at the beginning of the last century that die casting was widely used in industry. 1905 Dohler (H. H. Dohler) developed a die casting machine for industrial production, die casting zinc, tin, copper alloy castings. Wagner then designed a gooseneck pneumatic die casting machine to produce aluminium alloy die castings.

Die casting characteristics

1.Wide range of die casting

2.The casting has high dimensional accuracy and low surface roughness

3.High productivity

4.High utilization rate of metal

5.High strength and surface hardness of casting

Surface treatment

Aluminum phosphide

The effects of promoters, fluoride, Mn2+, Ni2+, Zn2+, PO4 and Fe2+ on the phosphating process of aluminum were studied in detail by means of SEM, XRD, potential time curve and film weight change. The RESULTS SHOW THAT GUANIDINE NITRATE HAS THE CHARACTERISTICS OF GOOD WATER SOLUBILITY, LOW DOSAGE AND RAPID FILM FORMATION, AND IS AN effective promoter OF PHOSPhating of aluminum.

Fluoride can promote film formation, increase film weight and refine grain size. Mn2+ and Ni2+ can obviously refine the grain, make the phosphating film uniform and dense, and improve the appearance of the phosphating film. When the concentration of Zn2+ is low, the film can not form or the film is poor, and the film weight increases with the increase of Zn2+ concentration. PO4 content has a great influence on the weight of phosphating film and increases PO4. Content makes the weight of phosphating film increase.

Alkaline electrolytic polishing of aluminum

The alkaline polishing solution system was studied, and the effect of corrosion inhibitor and viscosity agent on polishing effect was compared. The alkaline solution system with good polishing effect was successfully obtained, and the additive which could reduce the operating temperature, prolong the service life of the solution and improve the polishing effect was obtained for the first time. The experimental results show that adding appropriate additives to NaOH solution can produce good polishing effect.

The exploratory experiment also found that the reflectivity of aluminum surface could reach 90% after using NaOH solution of glucose for DC constant pressure electrolytic polishing under certain conditions. However, due to the unstable factors in the experiment, further research is needed. The feasibility of using DC pulse electrolytic polishing method to polish aluminum under alkaline condition was explored. The results show that the leveling effect of DC constant pressure electrolytic polishing can be achieved by using the pulse electrolytic polishing method, but the leveling speed is slow.

Environmental protection chemical polishing of aluminum and aluminum alloys

Determine the development of a new environmentally friendly chemical polishing technology based on monophosphate-sulphuric acid, which will achieve zero NOx emission and overcome the quality defects of previous similar technologies. The key to the new technique is to add some compounds with special effects to the base liquid instead of nitric acid. Therefore, it is necessary to analyze the chemical polishing process of aluminum triple acidification, especially the role of nitric acid.

The main role of nitric acid in aluminum chemical polishing is to inhibit pitting corrosion and improve polishing brightness. Combined WITH THE CHEMICAL polishing experiments IN PURE MONOPHOSPHATE-SULPHURIC ACID, IT IS concluded that the special substances added IN MONOPHOSPHATE-SULPHuric acid should be able to inhibit the pitting corrosion, slow down the overall corrosion, and must have good leveling and shining effect

Electrochemical surface strengthening of aluminum and its alloys

The TECHNOLOGY, PROPERTIES, morphology, composition and structure of ceramic amorphous composite transformation film FORMED by anoDIZING deposition of ALUMINUM and its alloys in NEUTRAL system were studied. The results show that in the neutral mixed system of Na_2WO_4, the concentration of film forming promoter is 2.5 ~ 3.0g/l, the concentration of complexing film forming agent is 1.5 ~ 3.0g/l, the concentration of Na_2WO_4 is 0.5 ~ 0.8g/l, the peak current density is 6 ~ 12A/dm~2, and the concentration of Na_2WO_4 is weak stirring. Can obtain complete uniform, good gloss gray series inorganic non – metallic film. The thickness of the film is 5-10 μm, the microhardness is 300 ~ 540HV, and the corrosion resistance is excellent. The neutral system has good adaptability to aluminum alloy, and can form film well on many series of aluminum alloys, such as antirust aluminum and forged aluminum.