Interactions of polymeric components in a POM-based binder system for titanium metal injection moulding feedstocks

Figures & data

Table 1. Binder weight content (wt-%) used for feedstock preparation.

Binder	POM (%)	PP (%)	EGMA (%)	E40 (%)	SA (%)
C-0	80	15	0	0	5
EGMA-3	77	15	3	-	5
E40-3	77	15	-	3	5

Figure 1. The FTIR spectra of feedstock (a) C-0, (b) EGMA-3 and (c) E40-3 with its respective binder constituent.

Figure 2. Possible interactions between POM and different compatibilisers in the binder system.

Figure 3. AFM phase images (with optical micrograph) of the POM-based binder system with formulation (a) C-0, (b) EGMA-3 and (c) E40-3.

Figure 4. SEM fractographs on TITANIUM MIM feedstock (green parts) with binder formulation (a) C-0, (b) EGMA-3 and (c) E40-3.

Table 2. Contact angle [^o] and calculated free surface energy (10⁻³J m⁻²) of the binder components on four different liquids (deionised water (DI), ethylene glycol (EG), di-iodomethane (DIM) and hexadecane (HD.)).

Materials	DI	EG	DIM	HD	γ^(tot)	γ^(d)	γ^(p)
POM	82.8	74.5	29.6	20.2	36.3	32.4	3.9
PP	88.1	72.3	44.7	12.2	33.2	30.9	2.3
EGMA	82.2	74.9	48.9	40.9	30.9	27.8	3.1
E40	87.9	80.4	56.6	51.2	26.6	23.8	2.8

Table 3. The interfacial tension of the binder components using geometric and harmonic mean equations.

	γ ^(Interfacial Tension) (10^−3 J m^−2)
	Geometric mean	Harmonic mean
POM/PP	1.21	2.39
POM/EGMA	0.69	1.37
POM/E40	1.05	2.09
PP/EGMA	0.54	1.05
PP/E40	0.69	1.37

Figure 5. Contact angle of the POM-based binder system with different compatibiliser compositions. Note that F.C-0, F. EGMA-3 and F.E40-3 represent feedstock C-O, EGMA-3 and E40-3.

Table 4. Pycnometer density of feedstock C-0 and EGMA-3 at three different conditions.

Sample condition	Experimental density (g/cm^3)	Theoretical density (g/cm^3)	% Density (g/cm^3)
C-0
Feedstock	3.3417 ± 0.012	3.3049	101.11
Moulded Part	3.2810		99.28
Crushed moulded part	3.2793		99.23
EGMA-3
Feedstock	3.1768 ± 0.009	3.2982	98.32
Moulded Part	3.2836		99.56
Crushed moulded part	3.2810		99.48

Figure 6. The log-log plot of viscosity vs shear rate plot of feedstock (a) C-0 and (b) EGMA-3 in the temperature range of 180–200°C.

Figure 7. The comparison between the poor (a) and good (b) flow behaviour of feedstock. A stable feedstock will have a consistent flow and extrude nicely through the capillary die.

Table 5. The (n−1) value and moldability index for feedstock C-0 and EGMA-3 at three different temperatures.

Temperature (°C)	180°C	190°C	200°C
Feedstock C-0
(n−1)	−0.467	−0.375	−0.293
Moldability index, α	4.37E-03	4.88E-03	4.30E-03
Feedstock EGMA-3
(n−1)	−0.441	−0.466	−0.406
Moldability index, α	7.13E-03	8.31E-03	9.25E-03

Figure 8. Temperature dependence of viscosity for feedstock C-0 and EGMA-3 at a shear rate of 6000 s⁻¹.