Table 7.

Orthogonal table of the sintering parameters and hardness of the sintered samples.

NO.	Heating Rate (°C/min)	Highest Temperature (°C)	Holding Time (h)	Vickers Hardness (HV)
1	3	950	1	10.42 ± 0.87
2	3	1000	2	14.97 ± 1.02
3	3	1083	3	63.04 ± 0.60
4	5	950	3	16.12 ± 0.91
5	5	1000	1	14.85 ± 1.34
6	5	1083	2	54.65 ± 2.92
7	8	950	2	12.12 ± 1.55
8	8	1000	3	21.72 ± 1.45
9	8	1083	1	52.98 ± 4.60
$\overline{y}$j1	29.48	12.89	26.08	${\displaystyle \sum _{i=1}^9{y}_i}=257.55$
$\overline{y}$j2	28.54	17.18	27.25
$\overline{y}$j3	28.94	56.89	33.62
RJ	0.94	44	7.54
Primary and secondary factors	Highest temperature > Holding time > Heating rate
Optimal combination	Heating rate (3 °C/min)—Highest temperature (1083 °C)—Holding time (3 h)