Mechanical properties of rice husk ash, an environmental pollutant, based composites: A step towards sustainable hybrid composites

Figures & data

Figure 1. Reinforcement material (a) RHA (b) Al₂O₃ (c) SiC (d) ZrSiO₄.

Table 1. Mechanical and physical properties of SiC, Al₂O₃, RHA and ZrSiO_4.

	Specific Gravity	Bulk Density (g/cc)	D50 Malvern (µm)	Hardness Mohr’s scale:	Colour	Size (µm)
Zirconium Silicate (ZrSiO4)	4.5	0.8	1.40–1.65	-	White
SiC	3.2	-	-	9.2	Black	04
Al2O3	3.9	-	-	9	White	03
RHA						40-50

Figure 2. Schematic view of the stir casting process.

Figure 3. Photographic view of the stir casting process.

Figure 4. Tensile test specimen: (a) Schematic view (all dimensions are in mm); (b) Photographic.

Table 2. Chemical composition of Al6061.

Cu	Si	Mg	Mn	Fe	Ti	Zn	Al
0.15–0.4	0.4–0.8	0.8–1.2	Max 0.15	Max 0.7	Max 0.15	Max 0.25	Bal

Table 3. Chemical and physical properties of Silicon Carbide (SiC), Al₂O₃, ZrSiO₄ and RHA.

Chemical Properties of SiC (%)			Chemical Properties of ZrSiO4 (%)
SiC	Free Carbon (FC)	Fe2O3	ZrO2+HfO2	SiO2	Al2O3	TiO2	Fe2O3	-
93-98	0.1–0.2	0.1–0.2	64.4	34.1	0.8	0.15	0.07	-
Chemical Properties of Al2O3 (%)			Chemical Properties of RHA (%)
Al2O3	SiO2	Fe2O3	SiO2	Al2O3	Fe2O3	Na2O+K2O	CaO	Free Silica Sand
96-99	0.03–0.8	0.03–0.1	88.9	2.5	2.19	0.69	0.22	Max. 3%
Physical Properties
						SiC	Al2O3	ZrSiO4
Hardness (Mohrs Scale)						9.2	9	4.5
Specific gravity						3.2	3.9	-
Size (µ)						04	03	1.4–1.65
Bulk density (g/cc)						-	-	0.8

Table 4. Physical properties of RHA.

Colour	Specific gravity	Bulk Density (Loose)	Bulk Density (Tamped)	pH of 10% Slurry	pH of 4% Slurry	Rate of filtrations per min	Material Passing through 100 Mesh	Material Passing through 300 Mesh	Moisture	Oil absorption
Off White	2.25	1.52 kg/m^3 and 0.39 gm/cc	1.87 kg/m^3 and 9.98 gm/cc	7.7	7.4	5.55	77.55%	38.52%	0.11%	97.85%

Table 5. Composite reinforcement wt%.

	SiC (wt%)	Al2O3 (wt%)	ZrSiO4 (wt%)	RHA (wt%)
Base	0	0	0	0
A	1	1.1	0.8	1.6
B	1.5	1.1	0.7	1.2
C	2	1.1	0.6	1.0

Figure 5. Tensile testing tensometer setup.

Table 6. Specification of tensometer.

Sr. No.	Parameters	Value
1	Capacity	20 kN max. (2,000 kg)
2	Dimensions	H300 x W700 x L1050 mm (approx.)
3	Weight	60 kg (approx.)
4	Servo motors	Permanent D.C. Servo, 3.6V, 4.8A, 1,600 RPM, 0.16 kV
5	Load cells available	0.2, 2, 5, 10 and 20 kN
6	Graph of the test	On-line graph through PC software
7	Computer interface facility	Computer-controlled machine

Table 7. Specification of hardness testing machine.

Sr. No.	Parameters	Unit	Value
1	Initial Load (Minor)	kN	0.098
2	Maximum testing Height	mm	380
3	Depth of throat	mm	200
4	Dia. Of the ball indenter	mm	2.5
5	Max. depth of elevating screw below the base	mm	180
6	Size of Base	mm	370 x 670
7	Machine height	mm	1,185
8	Net weight (approx.)	kg	500

Figure 6. Scanning electron microscope images of (a) Sample a (b) Sample B (c) Sample C.

Figure 7. EDAX graph of AMMHCs.

Table 8. Chemical composition of AMMHCs.

Element	C K	O K	Mg K	Al K	Si K	Fe K	Zr K	Total
Wt%	20.3	3.9	0.8	69.5	2.0	0.2	3.4	100.0
Atomic %	36.3	5.2	0.7	55.4	1.5	0.1	0.8	–

Figure 8. Variation of ultimate tensile strength (σ_ut) with reinforcement.

Figure 9. Variation of yield stress (σ_yt) with reinforcement.

Figure 10. Variation of % of elongation (ε) with reinforcement.

Figure 11. Variation of breaking strength (σ_b) with reinforcement.

Figure 12. Brinell hardness variation for Al6061–SiC composite with increasing SiC