Aluminum titanate lift liquid pipe

The key component of the “anti-gravity” casting- -the ceramic liquid lifting tube

 In ancient times, we have mastered the metal thermal processing technology of casting- -the metal smelting into a liquid that meets certain requirements and cast into the casting, after cooling solidification, cleaning treatment to get the predetermined shape, size and performance of the casting process is casting, such as the earliest bronze added into the picture. The thin-walled of mold is the development direction of modern casting technology and the premise of the development of lightweight products. It is of great significance to realize the thin-walled of casting in aerospace, automotive, electronics and other fields. Filling type is the key to the manufacturing technology of thin-wall castings. Large complex thin-wall castings have fast heat dissipation, short solidification time and high filling resistance. Therefore, its casting forming has always been one of the difficulties in the manufacturing industry, and it is especially difficult to cast the forming of large complex thin-wall castings of superalloy.

 Antigravity casting, due to its reasonable temperature field distribution, smooth filling characteristics and good liquid shrinkage ability, has been widely used in the production of high quality aluminum magnesium alloy casting, and become the mainstream forming technology, especially in the production of large complex thin-walled quality components is almost become irreplaceable means of production. Casting can be divided into low pressure casting, differential pressure casting, pressure regulating casting and vacuum suction casting.

1. What is anti-gravity casting?

 Antigravity inside the gravity perceived in normal life. Before you look at antigravity casting, first look at the concept of gravity casting. Gravity casting refers to the casting of metal liquid under the action of earth gravity, also known as gravity casting, generalized gravity casting includes sand casting, metal casting, melt casting, disappear die casting, mud casting, etc. Narrow sense gravity casting mainly refers to metal casting.

Antigravity casting (Counter-Gravity Casting, CGC) is a casting casting forming process developed in the 1950s, which is the application of Pascal principle in casting production. It is a method to make the metal in the crucible to overcome the gravity and other resistance along the rising pipe under the action of pressure, and to obtain the casting under pressure. It is characterized by the driving force of the alloy liquid filling casting is opposite to the gravity direction, and the alloy liquid flows in the opposite direction to the gravity.

Pascal principle

Transfer of the liquid pressure

Pressure added to a closed liquid,

S2 15

Be able to size unchanged to each side

ECT FS

To pass, this law is called

A strange

Pascal principle.( P1=P2)

 Pascal’s principle: the pressure transfer of the liquid.

 The metal liquid in antigravity casting is actually filled under the common action of gravity and the applied driving force. The external driving force is the dominant force in the process of metal liquid filling, which enables the metal liquid to overcome its own gravity, type cavity resistance and other external forces to complete the filling and casting type. Due to the existence of external driving force, antigravity casting becomes a controllable process. In the process of metal liquid filling, the filling of different filling speeds can be realized by controlling the applied force; and the casting is solidified under a strong action, and the filling and shrinkage ability of the metal liquid is improved, and the casting defects such as shrinkage hole, stoma and pinhole are reduced.

Antigravity forming technology can be parameterized throughout the forming process to realize the process of reproducible, which is widely used in the production of high quality castings. Antigravity casting is suitable for a wide range, can be used in aluminum alloy, magnesium alloy, copper alloy, titanium alloy, titanium alloy, high temperature alloy and other materials, casting weight from dozens of grams to several tons.

2. One of the key components of anti-gravity casting: the lifting tube

Lifting tube is one of the key components of antigravity casting. When filling, under the action of air pressure, the metal liquid enters the cast from the crucible through the ascending pipe. During pressure relief, the unsolidified metal liquid is also returned into the crucible through the ascending tube. As an important component in the pouring system, the lifting tube has the function of diversion and contraction. It should have air tightness, chemical inertia and stable reliability of filling process, and plays a vital role in the anti-gravity casting process. The ascending tube can be made of different materials, from the material, the ascending tube is mainly divided into metal ascending tube and ceramic tube. During the die-casting process, the aluminum melt (temperature 700~900℃) is pressed to the mold cavity from the liquid draft tube every 3~5 minutes. The liquid lifting tube must have low thermal expansion coefficient and good thermal shock resistance to improve the service life of the liquid lifting tube.

1. Metal liquid lifting tube

Metal hydraulic pipe is mainly made of seamless steel pipe welding or gray cast iron casting, inner and outer brush with fire-resistant coating. Metal tube is the advantage of good mechanical properties, good air tightness, easy to processing, low price, deficiency is the difference between thermal expansion coefficient of metal and coating, coating easy to peel, metal tube easy to corrosion, pollution alloy, and metal tube deformation in use, will affect the flow rate and direction of alloy liquid. In addition, the service life of cast iron liquid pipe is short, and the time of replacing parts affects the production efficiency.

2, aluminum titanate ceramic lifting tube

 Aluminum titanate ceramics not only have a high melting point (1860℃), a low thermal expansion coefficient (α 2.010-6 / K), but also have the characteristics of many non-ferrous metals such as aluminum, so it is an excellent material for the manufacture of liquid raising tubes for cast aluminum. However, aluminum titanate is easily decomposed into α -Al2O3 and rutile TiO2 at 750~1300℃, which results in reduced material mechanical properties and thermal shock resistance. The domestic research on aluminum titanate ascending liquid tube mainly focuses on improving its thermal shock resistance. Compared to traditional cast iron risers (the same is true for silicon nitride and Ceron ceramics mentioned below), so heat can be maintained during low pressure die casting.

Aluminum titanate lift liquid pipe, good product service life 3 months +, ordinary product service life about ten days. Aluminum titanate pipe used for a long time, better cost performance, widely used.

3. Silicon nitride ceramic liquid-raising tube

 As an advanced refractory material, silicon nitride has the advantages of low thermal expansion coefficient, good heat impact resistance, high high temperature mechanical properties and strong metal erosion resistance. The melting point of silicon nitride is 1900℃, and the thermal expansion coefficient is 2.510-6 / K, which does not moisten many metals. Pure silicon nitride lift tube has better heat shock resistance and temperature resistance than aluminum titanate lift tube, long service life but expensive.

Silicon nitride lifting tube, expensive, but very durable, is said to do a good life of 14 months +; using silicon nitride combined with silicon carbide lifting tube normal continuous operation service life is more than 30 days, the use of cost performance is also good. Compared with other materials, it has better durability, but the cost is relatively high, to choose the appropriate balance point, comparative performance and life for material selection.

4. Selon ceramic liquid lifting tube

 Theron ceramic is a Si3N4-Al2O3 series high temperature sintering material, which is partially converted by Al2O3 Al and O atoms into the Si and N atoms in Si3N4, forming the Si-Al-O-N system. Ceron ceramics has the advantages of good high temperature strength, excellent stable chemical performance at room temperature and high temperature, good wear resistance, low thermal expansion coefficient (2.4~3.210-6 / K) and good heat impact resistance.

Theron ceramics combines the comprehensive performance of silicon nitride (high strength, hardness, fracture toughness and low thermal expansion) and alumina (corrosion resistance, chemical inertia, high temperature ability and oxidation resistance), with very excellent thermal and mechanical properties. According to the data, the selon ceramic liquid lift tube produced by a professional company has excellent heat impact resistance and a service life of up to 12 months.

5. Composite material liquid lifting tube

The composite material hydraulic tube is mostly made of cast steel and heat resistant steel as the skeleton, and the internal and external surfaces are coated or embedded with high-temperature resistant ceramics and other non-metallic materials of a certain thickness. It has the advantages of good air tightness and high mechanical properties of the metal hydraulic tube, as well as the high temperature resistance and high temperature chemical stability of non-metallic materials. The manufacturing process of such lifting tubes is complex and the cost is high.

Compared with the above, the aluminum titanate series of ceramics are introduced as follows:

1. Product production background:

Aluminum titanate (Al 2 TiO 5) is a refractory compound made of a mole of alumina (Al 2 O 3) and a mole of titanium dioxide (TiO 2). This polycrystalline ceramic material is usually prepared by the reaction sintering of alumina and titanium dioxide powder to form a stoichiometric proportional solid solution. Due to its good chemical resistance, low thermal conductivity and high thermal shock resistance (due to low thermal expansion coefficient), aluminum titanate can become a suitable material for various technology applications, such as casting parts (nozzle, crucible, gate)), motor vehicle converter and glass industry mold aluminum titanate series ceramics with high room temperature and high temperature strength, corrosion resistance and low thermal expansion resistance, no slag, no cracking, long service life and no infiltration with aluminum solution characteristics, make it a metallurgical low pressure casting industry for liquid pipe, water, outlet ideal material. At present, high quality liquid lifting tube is still mainly dependent on imports, one is the high cost, two is the continuity of production can not be guaranteed. The birth of aluminum titanate composite ceramic liquid lifting tube has far-reaching significance for the transformation and promotion of China’s traditional industrial technology and the revitalization of automotive electronics industry.

 Product features:

1. Excellent heat and impact resistance. Aluminum titanate (Al 2 TiO 5) is characterized by its excellent heat and shock resistance. Despite the low strength variation, the parts made from this material can even withstand it.

2, with aluminum melt and other nonferrous metal solution does not infiltrate. Aluminum titanate is a ceramic material that cannot be moistened by liquid aluminum and is also known for its excellent heat shock resistance.

3, higher room temperature and high temperature intensity.utmost. Operating temperature: extremely low thermal expansion of 900℃ (<1×10-6 K 0-1 between 20 and 600°C) high insulation (1.5 W / mK).

4, excellent wear and corrosion resistance. Low Young’s modulus (17 to 20 GPa) has good chemical resistance and poor wettability of the molten metal. Excellent chemical resistance and wear resistance ensures high melt purity.

5, and a lower thermal expansion coefficient. Aluminum titanate can easily cope with the challenging conditions in the non-ferrous molten metal industry, because traditional materials simply cannot withstand the heat of the industry.

6, with a low thermal conductivity. This makes aluminum titanate tubes ideal for aluminum foundries. Its low thermal conductivity can save energy, it has incomparable heat shock impact behavior, usually used to withstand the high thermal stress level of components, can make the low pressure casting machine in the production process to achieve its automation and continuity, so as to improve its production efficiency, reduce the production cost.

3. Product performance indicators:

4. size of product:

Note: Various types of aluminum titanate lifting tubes can be processed according to customer needs.