Silicon bronze

A special type of bronze having silicon as the main alloying element. In addition to silicon, manganese, nickel, zinc and other elements are added. Silicon bronze has good mechanical properties, good corrosion resistance, wear resistance, good weldability, easy to process, non-magnetic, no sparks when impact, and does not lose the original characteristics of the material at low temperature, it is often used as liquid gas and gasoline storage parts, elastic components and wear resistant parts. Common mark such as QSi3-1,QSi1-3 and so on. At 852℃, the maximum solubility can reach 5.3%, which decreases with the fall of temperature. However, the aging hardening effect is not strong, so the intensified heat treatment is generally not carried out. The content of deformed silicon bronze is 1% ~ 4%, and the increase of silicon will lead to brittle phase and decrease plasticity. Silicon bronze has a small crystallization temperature range, sufficient fluidity and higher mechanical properties than tin bronze, so it can be used as a substitute for tin bronze in mechanical manufacturing industry.

Chemical properties
Silicon bronze rod has strong corrosion resistance to atmosphere, water gas, natural fresh water and sea water. Due to the formation of a dense and solid chloride film on its surface, but their flow rate cannot exceed 1.5m, otherwise, the oxide film will be destroyed and lose its protection. If the temperature is over than 60℃ or the water contains CO2 and oxygen, the erosion rate is accelerated.
Silicon bronze rod has high corrosion resistance to alkali solution with low concentration and low temperature. However, the increase of temperature or concentration will lead to the increase of erosion rate. Acidic water containing Fe2 (SO4) 3 will strongly erode the silicon bronze rod, because Fe2 (SO4) 3 has the effect of cathode depolarization. Solutions of chromate, ferric chloride, and concentrated zinc chloride will strongly erode the silicon bronze rod. Dry chlorine, hydrogen fluoride, hydrogen sulfide, hydrogen chloride, sulfur dioxide, ammonia and carbon tetrachloride will not erode the silicon bronze rod, if it contains water gas corrosion effect on the silicon bronze rod. Acetylene, ammonium hydroxide, ammonium chloride, chromate, ferric chloride, ferric sulfate, mercury, mercury salts, nitric acid, potassium cyanide, sodium hydride, potassium dichromate, silver salts, sodium hydrogen chloride, molten sulfur, and cyanic acid all erode silicon bronze rods. There are two grades of deformed silicon bronze listed in Chinese national standard.

Influence factor
The mechanical properties, corrosion resistance and technological properties can be improved by adding proper manganese to copper silicon alloy. Silicon bronze QSi3-1 containing silicon 3% and manganese 1% is often used. It is a single-phase solid solution at high temperature. When cooled to below 450℃, a small amount of compound Mn2Si or MnSi will be precipitated, but the strengthening effect is very weak. Due to phase transition stress, QSi3-1 bars are prone to self-cracking during storage, so the finished products should be annealed at low temperature and the appropriate lower limit of alloy silicon content should be obtained. QSi3-1 silicon bronze can be processed under pressure in cold and hot conditions, with good mechanical, corrosion resistance, wear resistance and welding performance, no magnetism, and no spark during impact. It is widely used in machinery, chemical industry, petroleum, shipbuilding and other industrial sectors.
Nickel can improve the mechanical properties and corrosion resistance of silicon bronze, and also has good conductivity. Nickel and silicon form a copper-soluble compound called Ni2Si, whose maximum solubility is 9.0% at eutectic temperature (1025°C) and decreases with falling temperature to zero at room temperature. Copper alloy with a ratio of 4:1 nickel to silicon will be strengthened by Ni2Si phase precipitation during aging treatment, and good comprehensive properties will be obtained. Silicon bronze QSi1-3, which is commonly used in industry and contains 1% silicon and 3% nickel, has good plasticity after quenching at 900 ~ 950℃. After quenching at 350 ~ 550℃ for 1 ~ 4H, its strength can be doubled. This alloy has high wear resistance and high temperature strength. Its conductivity is also higher than the general copper alloy. Therefore in the mechanical industry and other sectors of the manufacturing of important parts, but also for communications with high strength overhead wires and conductive poles. Lead, antimony, bismuth, arsenic, sulfur, phosphorus and other elements are harmful to the alloy and should be strictly controlled.

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