The Effect of Titanium Carbide and Spark Plasma Sintering …
67
Experimental Details
Glovebox filled with argon used for an elemental mixture of nickel (mean particle
size 3–7 µm, 99.9%, Alfa Aesar), TiC (mean particle size 2 µm, 99.5%, Alfa Aesar)
powders, stearic acid, and 5 mm tungsten carbide (WC) balls were sealed into lined
WC milling container. The ball to powder ratio was 10:1, and 3% of steric acid was
added for mechanical alloying in high energy planetary ball milling (Pulverisette 7
Premium, Fritsch, Germany) for 24 h at 400 rpm to create a homogenous mixture
of powder for sintering. The MA powder sintered (SPS 10-3, Thermal Technology
LLC, California, USA) in an argon atmosphere at 900 °C (for the 5, 10, 25 wt.% TiC)
with 65 MPa with a holding time of 5 min using a 20 mm graphite die. Additional
samples were prepared using a 10 mm diameter graphite die for compression testing.
The sintered sample was having a 20 mm diameter and 2 mm thickness. All
samples were cooled to room temperature to remove any large inconsistencies and
then mounted (TechPress 3, Allied High-Tech Products Inc., California, USA) in a
graphite mounting material for further polishing. Mounting samples were ground
(AutoMet 250, Buehler, Illinois, USA) at ∼55 N using 250, 400, 600, 800 and
1200 grit sandpaper sequentially for 5–30 min each (increasing time with grit). After
grinding, the samples were rinsed with deionized (DI) water then polished (VibroMet
2, Buehler, Illinois, USA) for ∼18 h. The samples were then ultrasonically cleaned
(3800, Branson Ultrasonics, Connecticut, USA) for approximately 10 min in a DI
water and soap bath and then for 10 min in an alcohol bath to remove the silica from
the surface.
The surface morphology of each sample was analyzed by using scanning electron
microscopy (SEM) (Inspect F50, FEI, Oregon, USA) for grain size and porosity
analysis. X-ray diffraction for bulk samples was performed using Rigaku Ultima
III X-ray diffractometer with Cu Ka radiation. Vickers hardness (Wilson VH1202,
Buehler, Illinois, USA) testing was done on each sample using the HV0.5 scale at
10 test points (Table 1).
Table 1 Characteristics of Ni and TiC powders
Reagent Density (g cm −1 ) Mean particle size (µm) Purity (%) Source
Ni
8.9
3–7
99.9
Alfa Aesar, United States
TiC
4.9
2
99.5
Alfa Aesar, United States
67
Experimental Details
Glovebox filled with argon used for an elemental mixture of nickel (mean particle
size 3–7 µm, 99.9%, Alfa Aesar), TiC (mean particle size 2 µm, 99.5%, Alfa Aesar)
powders, stearic acid, and 5 mm tungsten carbide (WC) balls were sealed into lined
WC milling container. The ball to powder ratio was 10:1, and 3% of steric acid was
added for mechanical alloying in high energy planetary ball milling (Pulverisette 7
Premium, Fritsch, Germany) for 24 h at 400 rpm to create a homogenous mixture
of powder for sintering. The MA powder sintered (SPS 10-3, Thermal Technology
LLC, California, USA) in an argon atmosphere at 900 °C (for the 5, 10, 25 wt.% TiC)
with 65 MPa with a holding time of 5 min using a 20 mm graphite die. Additional
samples were prepared using a 10 mm diameter graphite die for compression testing.
The sintered sample was having a 20 mm diameter and 2 mm thickness. All
samples were cooled to room temperature to remove any large inconsistencies and
then mounted (TechPress 3, Allied High-Tech Products Inc., California, USA) in a
graphite mounting material for further polishing. Mounting samples were ground
(AutoMet 250, Buehler, Illinois, USA) at ∼55 N using 250, 400, 600, 800 and
1200 grit sandpaper sequentially for 5–30 min each (increasing time with grit). After
grinding, the samples were rinsed with deionized (DI) water then polished (VibroMet
2, Buehler, Illinois, USA) for ∼18 h. The samples were then ultrasonically cleaned
(3800, Branson Ultrasonics, Connecticut, USA) for approximately 10 min in a DI
water and soap bath and then for 10 min in an alcohol bath to remove the silica from
the surface.
The surface morphology of each sample was analyzed by using scanning electron
microscopy (SEM) (Inspect F50, FEI, Oregon, USA) for grain size and porosity
analysis. X-ray diffraction for bulk samples was performed using Rigaku Ultima
III X-ray diffractometer with Cu Ka radiation. Vickers hardness (Wilson VH1202,
Buehler, Illinois, USA) testing was done on each sample using the HV0.5 scale at
10 test points (Table 1).
Table 1 Characteristics of Ni and TiC powders
Reagent Density (g cm −1 ) Mean particle size (µm) Purity (%) Source
Ni
8.9
3–7
99.9
Alfa Aesar, United States
TiC
4.9
2
99.5
Alfa Aesar, United States