Aluminum alloy die-casting products are mainly used in electronics, automobiles, motors, home appliances and some communication industries. Some high-quality aluminum alloy products with high performance, high precision and high toughness are also used in industries with relatively high requirements such as large aircraft and ships. Main use is still on parts of some instruments.

 

There are different opinions on development history of die-casting. According to records of relevant articles, die-casting lead first appeared. In 1822, William Church built a casting machine with a daily output of 12,000 to 20,000 lead type. After more than 20 years, J.J.Sturgiss (J.J.Sturgiss) designed and created the first manual piston hot chamber die-casting machine, and obtained a patent in the United States. In 1885, Mergenthaler studied previous patents and invented printing die-casting machine. It was used in production of zinc alloy die-casting parts until the 1860s. It was only at the beginning of last century that die casting was widely used in industrial production. In 1905, H.H.Doehler successfully developed die-casting machines, die-cast zinc, tin and copper alloy castings for industrial production. Wagner then designed a gooseneck pneumatic die-casting machine for production of aluminum alloy die-casting parts.

1. Wide range of die casting
2. Castings have high dimensional accuracy and low surface roughness
3. High productivity
4. High metal utilization rate
5. High casting strength and surface hardness
Surface treatment editor broadcast

Effects of accelerators, fluorides, Mn2+, Ni2+, Zn2+, PO4 and Fe2+ on phosphating process of aluminum were studied in detail by using methods such as SEM, XRD, potential-time curve, and film weight change. Studies have shown that guanidine nitrate has characteristics of good water solubility, low dosage and rapid film formation, and is an effective accelerator for aluminum phosphating. Fluoride can promote film formation, increase film weight, and refine grains; Mn2+ and Ni2+ can significantly refine grains, make phosphating film uniform and dense, and can improve appearance of phosphating film; when concentration of Zn2+ is low, film cannot be formed Or poor film formation, as Zn2+ concentration increases, film weight increases; PO4 content has a greater impact on phosphating film weight, increasing PO4 content will increase weight of phosphating film.

Research on alkaline polishing solution system was carried out, influence of corrosion inhibitors and viscosity agents on polishing effect was compared, and an alkaline solution system with good polishing effect was successfully obtained, it was the first time to obtain a solution that can reduce operating temperature and prolong use of solution. It is an additive that can improve polishing effect at the same time. Experimental results show that adding appropriate additives in NaOH solution can produce good polishing effect. Exploratory experiments also found that after direct current constant voltage electropolishing with glucose NaOH solution under certain conditions, reflectivity of aluminum surface can reach 90%, but due to unstable factors in experiment, further research is needed. Feasibility of using DC pulse electropolishing method to polish aluminum under alkaline conditions was explored. Results showed that pulse electropolishing method can achieve leveling effect of DC constant voltage electropolishing, but leveling speed is slow.

It is determined to develop an environmentally friendly new chemical polishing technology based on phosphoric acid monosulfuric acid. This technology must achieve zero emission of NOx and overcome quality defects of similar technologies in the past. Key to new technology is to add some compounds with special effects to replace nitric acid in base fluid. For this reason, it is first necessary to analyze three-acid chemical polishing process of aluminum, especially effect of nitric acid. Main function of nitric acid in aluminum chemical polishing is to inhibit pitting corrosion and improve polishing brightness. Combined with chemical polishing test in simple phosphoric acid-sulfuric acid, it is considered that special substance added in phosphoric acid-sulfuric acid should be able to inhibit pitting corrosion and slow down general corrosion, must have good leveling and brightening effects

 

Process, performance, morphology, composition and structure of ceramic-like amorphous composite conversion film formed by anodic oxidation deposition of aluminum and its alloys in a neutral system, film-forming process and mechanism of film are preliminarily discussed. Process research results show that in Na_2WO_4 neutral mixed system, concentration of film-forming accelerator is controlled at 2.5-3.0g/l, concentration of complex film-forming agent is 1.5-3.0g/l, and concentration of Na_2WO_4 is 0.5-0.8g/l, peak current density is 6-12A/dm~2, and weak stirring, a complete, uniform and glossy gray series inorganic non-metallic film can be obtained. Thickness of film layer is 5-10μm, microhardness is 300-540HV, and corrosion resistance is excellent. Neutral system has good adaptability to aluminum alloys, can form films on various series of aluminum alloys such as antirust aluminum and wrought aluminum.