The particle shape of titanium powder is spherical, polygonal, spongy and flake, etc. The particle shape is related to the preparation method of titanium powder. The requirements for titanium powder generally include three aspects, namely purity, particle size and particle shape.
The particle size of titanium powder is divided into four grades, the particle size of 1000-50pm is coarse powder, 50-10pm is fine powder, 10-0.5pm is micro-powder, and less than 0.5pm is ultra-fine powder. The purity of titanium powder includes titanium content and impurity content. The purity of titanium powder is related to its size, and the smaller the size of the product, the lower the purity. Usually titanium content greater than or equal to 99%, or close to 99% of the crude titanium powder is called grade products (if titanium alloy powder, should include alloy components), less than this composition of the product is called equal. In the grade. In addition to the requirements of special purposes, it is generally graded by oxygen content. That is, the lower the oxygen content, the better the quality and the higher the grade. High quality titanium powder with oxygen content less than 0.15%.
Aluminum alloy and titanium there is a method, one is to add the middle titanium alloy block, there are also filamentous; The second is to add titanium additives, which is to add titanium elements; The third is the addition of refiner, specifically refining the casting structure, not alloying elements, do not do composition analysis.
(1) Titanium additives. Titanium additives are used to adjust the titanium content in aluminum alloys. It is made of titanium and aluminum powder or flux salts pressed into blocks or cakes. Among them, the amount of titanium powder is 55%-75%, and the amount of aluminum powder or flux salt is 45%-25%, which is put into the melt aluminum alloy as required. If such additives use flux salts as ingredients, it should be noted that they cannot absorb moisture or contain moisture, in fact, the flux salts in the product are useless. Pure metal powder with packaging is most suitable.
(2) titanium refiner. The element of titanium refiner in the alloy is not the composition of the alloy, but the element that plays the role of thinning the organization in the melting and casting process, and is pressed into a block or cake supply after mixing titanium powder and salt chemicals. There are generally three kinds of titanium content. 30%, 40% and 60%, at the same time add boron-containing salt (boron content of 1%, 2%, 3% or 4%), the rest with NaCl and KC1 etc preparation. The market supplies Ti40B4, Ti30B4, Ti30B3 and Ti60Bl products.
In more than 150 kinds of deformed aluminum alloys, about 120 grades add titanium, but the amount of added is not large, between 0.02%-0.4%. In about 40 kinds of cast aluminum alloys, there are 13 grades with titanium, generally 0.08%-0.35%. The main purpose of adding titanium is to refine the casting structure and weld structure, reduce the casting crack tendency and improve the mechanical properties. The role of titanium is to form TiAl compound with titanium and aluminum, which acts as a non-spontaneous core and refines the cast structure when the aluminum alloy is solidified. Sometimes a small amount of B is added with Ti to form TiB2 compounds and promote the refinement of Ti.