2.1 powder -liquid ratio across the layer of coating thickness and suspension rate impact
Table
2 powder-liquid ratio on the opposite layer coating thickness and
coating suspension rates . The results show that the greater the surface
pulp powder -liquid ratio , the greater the thickness of the surface
coating , the coating suspension , the better. Generally believed that
if the surface coating is too thin (<0.2mm), the shell will be
affected by sanding the surface , the roughness increased. If the
coating is
material titanium too thick (> 0.6mm), the coating , poor mobility, easy
accumulation , during the drying or firing cracks easily [ 7 ] , which
in this study has also been confirmed in the present study therefore the
powder in the liquid ratio should be controlled between 5.0:1 - 6.0:1 .
Table 2 in the powder -liquid ratio of coating performance
Table2 Effects of solid / liquid ratios on the properties of coating
4.0:1 5.0:1 5.5:1 powder -liquid ratio 6.0:1
Coating thickness / mm 0.11 0.25 0.36 0.65
Coating suspension rate / % 88.3 90.1 93.1 97.6
2.2 Effect of shell powder -liquid ratio and calcination temperature on the room temperature and high residual strength
Figure
1 shows the ratio of powder and liquid at room temperature and high
temperature effect on residual strength . Strength of the sample is
composed of five levels of plasma and surface sand composition , each
drying 24h, continuous coating hanging , firing 4h. Flexural strength of
the strength test .
Figure 1 powder-liquid ratio of the residual strength of the opposite layer
Fig.1 Effects of S / L ratios on the remain flexural of
surface coats baked at different temperatures
The
results showed that the powder -liquid ratio improved shell specimen
bending strength . Calcination temperature is increased , the flexural
strength increases with . Since 1100 ℃ ZrO2 occurs near the phase
transition , so that the strength in the vicinity of this temperature
increase is not significant , but the phase change process , the lattice
of unstable energy increased activity increased , so should be avoided
in the actual production of the calcined temperature. After calcination
at 1200 ℃ by
titanium wire price the high ratio of powder and liquid coatings ( 6.5:1 )
intensity decreased slightly reason: Because the coating is too thick , a
slight increase in the calcination process of internal defects ,
thereby affecting its strength. From the results in Table 2 and Figure 1
show that the optimum value of 5.5:1 powder-liquid ratio of the surface
layer material . The firing temperature is preferably at about 1200 ℃,
but for small pieces of calcination temperature can be set at around
1000 ~ 1050 ℃.
2.3 Optimization of process parameters dewaxing
For
this study cast casting spade 150mm × 100mm , thickness of 2.5mm, the
microwave dewaxing process, the time relationship between the intensity
of the microwave shown in Figure 2 and dewaxing .
Figure 2 microwave intensity and dewaxing time
(a) the inner surface intact ; (b) inner surface microcracks
Fig.2 Effects of different
titanium rod for sale microwave intensities on dewaxing time
(a) no crack; (b) have cracks
Figure
in a district that is less than 70% when the microwave intensity ,
dewaxed shell inner surface smooth , with little residual wax, no
visible cracks. When the microwave intensity is too large (b zone ) ,
dewaxed shell intact , although overall , but there are a few cracks in
the surface layer , with the microwave intensity increased the number of
cracks increases , the reasons for this phenomenon may be due to over-
heating rate fast , since the internal stress of the inner and outer
layers of different thermal expansion coefficients of the time to
produce slack . Therefore microwave intensity used in this study was 50%
, dewaxing time about 8min. Through other experiments show that this
dewaxing process useful in the present
titanium rod stock study not only the spade member
is equally applicable to other shapes and sizes of parts.
