Metallic powder properties used in this study are given below. The 99.8% purity and particle size Fe powders less than 70 µm, were obtained from Sigma Aldrich. B4C powders having 99.9% purity and a particle size less than 100 µm from Egg Shelter powders were used. Composition of 98,33%Fe-1,66%B4C, 96,66%Fe-1,66%B4C-1,66% egg shelter, 95%Fe-1,66%B4C-3,32% egg shelter, 93,33%Fe-1,66%B4C-5% egg shelter and 91,66%Fe-1,66%B4C-6,66% egg shelter, powders were prepared. Powder samples were shaped with 30g circular uniaxial press. After weighing, the composition mixture was mixed in a mixer for 24 hours to ensure that the composition was homogeneous. The mixture was shaped by uniaxial cold hydraulic pressing using a high-strength steel mold. It was made under a pressure of 400 bar to compress all powder mixtures. Cold pressed samples were sintered at 1400°C for 2 hours in a conventional tube oven using an Argon gas atmosphere. After sintering, the samples were allowed to cool naturally under argon atmosphere in the oven. Micro hardness and shear strength of the samples were measured by METTEST-HT (Vickers) micro hardness tester, respectively. LEO 1430 VP equipped with the Oxford EDX analyzer in TUAM, was used for SEM microstructure and EDX analysis as a scanning electron microscope.
The density changes of the composite samples produced in 98,33&Fe-1,66%B4C, 96,66%Fe-1,66%B4C-1,66% egg shelter, 95%Fe-1,66%B4C-3,32% egg shelter, 93,33%Fe-1,66%B4C-5% egg shelter and 91,66%Fe-1,66%B4C-6,66% egg shelter composites were calculated using the sintering composite samples (d = m / V) formula (Figure 1). The volume of sintered samples was measured by the Archimedes principle. All percentages and ratios were given in percent by weight. The minerals contained in the eggshell powders were analyzed and determined in Table 1 (Yawar et al. 2020).
Table 1
Mineral composition of eggshell powders (Yawar et al. 2020)
Mineral
|
Egg Shelter powder
|
Calcium
|
39.62 ± 0.12 (%)
|
Magnesium
|
0.41 ± 0.01 (%)
|
Phosphorus
|
0.11 ± 0.00 (%)
|
Potassium
|
0.07 ± 0.00 (%)
|
Sodium
|
0.13 ± 0.00 (%)
|
Zinc
|
2.02 ± 0.00 (ppm)
|
Manganese
|
13.06 ± 0.01 (ppm)
|
Iron
|
1120 ± 4.5 (ppm)
|
Copper
|
0.96 ± 0.00 (ppm)
|
2.1 Experimental Results and Discussion
2.2 Characterization of specimens
The density-composition graph of the composite samples produced with metal martis and ceramic additives is given in figure.1. In the production of composite samples, the additive of eggshell powders was used atomically at different rates between 0% and 6,66%. The density was calculated as 5.28g/cm3 when eggshell powder was not added in the produced composite. When the eggshell powder was added 6,66% atomically, the density value was calculated as 5.93g/cm3. It was observed in SEM images that the addition of eggshell powder reduced the porosity in the composite.
The hardness values measured in the samples produced in Figure.2 were measured from 10 different points and given by taking the average. The lowest hardness value of 178,25HB was measured in the composite sample without eggshell powder added. Different compositions were obtained by increasing the eggshell powder atomically up to 6.66% in the sample composition. Among the produced samples, the highest hardness value was measured in the sample belonging to 204.12HB and 91.66%Fe-1,66%B4C-6,66% composition.
The maximum compressive strength change values of the produced compositions are given in Figure 3. Among the composite samples produced, the lowest compressive strength was measured at 210.52 Mpa in Fe-B4C composition. In the compressive strength test, the highest strength was measured at 274.18 Mpa in the samples belonging to the 91.66%Fe-1,66%B4C-6,66% eggshell composition. Density, hardness and microstructure pictures confirm these values.