grade 2 titanium wire Research Investment casting with titanium

Research Investment casting with titanium oxide ceramic shell -shell technology for

Titanium Investment casting technology to meet the needs of the aerospace grade 1 titanium wire industry and developed , has been widely used in aerospace titanium titanium components and civilian structures manufacturing. Practice has proved that the titanium alloy precision casting technology has become almost no margin of several forming processes to obtain maximum effectiveness of a process [ 1-3] . With the extensive application of titanium castings , its increasingly stringent quality and usability requirements , in addition, the level of costs also limit its application prospects is an important indicator . Graphite was low cost but poor quality of the casting surface , and is not suitable for the production of thin-walled complex parts [ 4 ] , but with the surface layer of refractory metal or yttrium oxide surface layer ceramic shell can be cast out of high quality titanium castings, but the cost is very high [ 5,6 ] . For this study the low -cost , suitable for the production of complex thin-walled shell technology for a new type of titanium oxide ceramic Investment casting is .

1 Materials and experimental methods

1.1 The main system shell material

Mold material : the material properties of the selected mode is shown in Table 1. The main use of imported wax wax casting specifically for titanium , gate part is low cost, performance can meet the requirements of homemade wax , respectively, after pressing, welding synthetic wax module.

Table 1 titanium casting mold materials with tungsten wire properties

Table1 Waxes used for making shells

Performance of imported wax homemade wax

Dropping Point / ℃ 69 ~ 71 70.5

Freezing point / ℃ 58 ~ 59 60 ~ 62

Linear shrinkage / % 1.3 0.4 0.6

Penetration / 1/10mm 12 ~ 14 11

Zhao hardness 21.1 19

Tensile strength / MPa 3.69 2.91

Adhesive wetting angle / ° 89 ~ 92 79 ~ 82

Density / g/mm3 0.91 ~ 0.94 0.95 ~ 1

Ash / % < 0.01 0.05

The surface layer and the adjacent surface layer of slurry : The main components of zirconia refractories , size of 30μm or less. Organic zirconium sol as a binder , the size of the refractory rubber match should be 10 ~ 15nm.

The surface layer and the adjacent surface layer of sanding : the main component of the surface layer is made of zirconium dioxide sand , the size of 150 ~ 300μm. To reduce costs, the use of adjacent surface layer is mainly composed of ZrO2.SiO2 zircon sand . The results show that the diffusion of Si is not seen in the casting , it is feasible the use of zircon sand .

Back layer system shell material: silica sol as a binder , using Morley powder and sand as refractories.

1.2 system shell method

The order of addition batter followed binders , refractory powder , trace additives. Minor amounts of additives to improve the stability of the coating role is to improve the wettability of the material and the mold , etc., and to prevent drying of the surface layer after the return water soluble additive is selected micro- organic material can be removed during the calcination . Stir batter than 2h at room temperature ( about 20 ℃) ​​in the air , titanium spring wire after the return of 1h to use .

O face the same batter pulp and raw materials , the production process is the same, only slightly smaller concentrations . Slurry feed back order binders , refractory powder. Also need to continuously stirred slurry back more than 2h , after the return of before use. Depending on the size of the backing layer casting , painted hanging normally takes 4-9 layers.

Drying : Drying time the surface layer and the adjacent surface layer are 24h, the temperature is 20 ℃, relative humidity of not less than 60% , the drying time of the backing layer is not less than 4h, the same as other conditions and the surface layer .