Calcium Thermal Reduction Of Titanium Trioxide To Prepare Porous Titanium And Its Pore Structure Characterization

Porous metal titanium is a composite material of titanium and gas.It is a new type of engineering material with dual function and structure.In recent years,titanium material with suitable pore structure and performance has become a research hot spot.The paper is based on the current research status of porous titanium,and based on the experiment which has been carried out on the preparation of titanium powder by calcium vapor reduction of titanium dioxide,combined with previous studies,proposing a new method for preparing porous titanium by calcium vapor reduction of Ti₂O₃:Mix and tablet a certain proportion of Ti₂O₃ and CaCl₂;Calciothermy is conducted to get Ti and CaO mixing block;Acid pickling to removal of CaO leaving the porous titanium skeleton;Vacuum sintering is to strengthen the structure strength and obtain the porous titanium with a certain pore characteristics.Preliminary inquiry found that the products on the cross section is divided into outer area with granular titanium and calcium oxide and the interior of the miscibility without obvious particle morphology.The outermost layer of the outer layer is the antler-shaped titanium particles connected to each other and become the surface titanium layer after leaching,and there is a calcium oxide concentration area inward which become gap after leaching.The inner region is still titanium and calcium oxide,which become the aggregated titanium particles with small size and has a loose structure after leaching.The study of the reduction products:The two regions in the product were always present when the reduction temperature was changed.As the reduction time is prolonged,the inner regions gradually increase and the outer regions are relatively reduced.When the Ti₂O₃/CaCl₂?wt%?=2,the morphology of product section is homogeneous,and is no obvious stratification and titanium particle aggregation area.When the Ti₂O₃/CaCl₂?wt%?=4,the two regions coexist at the same time,and when the Ti₂O₃/CaCl₂?wt%?=6,the mixed area of the lower part of the reduzate is formed,and the upper outer layer shows a decreasing trend.CaCl₂ promote migration of titanium particles which gathering in the surface,and making internal small size titanium particles mixed with calcium oxide particles,so that the reduction product cross section is formed on two different morphology.The analysis of leaching process shows that the effect of different reduction time and temperature on the structure integrity of leaching products is weak,and is influenced by the CaCl₂ content in raw materials.When the Ti₂O₃/CaCl₂?wt%?=2,the leaching product was completely scattered,and when Ti₂O₃/CaCl₂?wt%?=4 and 6,the porous titanium block was basically complete after leaching.The leaching product surface is the interconnected titanium particles.the particle size and pore size in the surface is almost not affected by the content of CaCl₂.And the Small particles of titanium gather inside.The connection of surface and internal are weak.The diameter of the surface titanium particles is between 10?m and 40?m,and the diameter of the closed hole is between 5?m and 30?m,and the diameter of the large hole which is not completely closed between 90?m and150?m.When the Ti₂O₃/CaCl₂?wt%?=4,there was a large decrease of the titanium particles with antlers in the interior,and the porosity was 73%.when theTi₂O₃/CaCl₂?wt%?=6,the antlers of titanium particles almost does not exist,and porosity reduce to 70%.The vacuum sintering obviously enhances the structural strength,but does not strengthen the connection between the surface and the interior.Particle size of titanium increase one to two times after sintering,and there are increased sintering neck and no obvious change in the pore.The diameter of closed pores is between 2?m and 25?m,and the diameter of the large hole is between 100?m and 120?m.At the same time,the large titanium particles increase in the sintered products.The porosity of the sample is less than before sintering,and decreases with CaCl₂ content reduce.when the Ti₂O₃/CaCl₂?wt%?=4,the pore porosity is 68%and Open porosity is 66%,when the Ti₂O₃/CaCl₂?wt%?=6,the pore porosity is 62%and Open porosity is 57%.