Composition, Structure and Properties of the Cr1-xAlxN Hard Films Deposited by Arc Ion Plating

doi:10.15541/jim20190353

Abstract

Abstract:

Four groups of Cr_1-_xAl_xN films with different Al contents were deposited on ultrafine cemented carbide substrates by arc ion plating, their morphology, composition, phase structure and mechanical property were investigated via field emission scanning electron microscope, X-ray photo electron spectrometry, grazing incidence X-ray diffraction, nanoindenter and scratch tests. The results revealed that the thickness of the films is 1.28, 1.42, 1.64 and 1.79 μm and the aluminum concentration x is 0.41, 0.53, 0.64 and 0.73, respectively, increased with incremental current of Al target. There is a close relationship between phase structure and composition. Films performed single centered cubic B1 structure when x is 0.41, however, demostrated mixed structure of c-(Cr,Al)N and hcp-AlN when x≥0.53. The dimensions of grains obtained a minimum value of 8.9 nm near x=0.64, as Al content increasing, while the variation in hardness followed an increase-decrease pattern, reaching peak values of 35.3 GPa at x=0.64. The films performed pretty adhesion strength and their critical loads were all over 60 N. Based on all test results, the Cr_1-_xAl_xN films exhibited the best combination properties including high hardness of 34.7 GPa, the highest elastic recovery coefficient of 57.4% and the best toughness while x is 0.53.

Key words: arc ion plating, Cr_1-_xAl_xN hard films, composition, phase structure, mechauical properties

CLC Number:

TQ174

MO Yajie,WANG Minglei,CHEN Weijie,LIN Guoqiang. Composition, Structure and Properties of the Cr_1-_xAl_xN Hard Films Deposited by Arc Ion Plating[J]. Journal of Inorganic Materials, 2020, 35(6): 675-681.

Figures/Tables 12

Fig. 1 Schematic diagram of enhanced magnetic filtered pulse bias arc ion plating apparatus

Table 1 Deposition parameters of Cr1-xAlxN films

Sample	N₂ flow/ sccm	Working pressure/Pa	Arc current/A		Pulsed bias			Deposition time/min
Sample	N₂ flow/ sccm	Working pressure/Pa	I_Cr	I_Al	Frequency/kHz	Amplitude/V	Duty cycle/%	Deposition time/min
CrAlN 1#	80	0.8	110	50	30	-200	40	120
CrAlN 2#	80	0.8	95	65	30	-200	40	120
CrAlN 3#	80	0.8	80	80	30	-200	40	120
CrAlN 4#	80	0.8	65	95	30	-200	40	120

Fig. 2 SEM surface and cross-sectional images of Cr1-xAlxN films (a,b) 1#; (c,d) 2#; (e,f) 3#; (g,h) 4#

Fig. 3 XPS spectra of Cr1-xAlxN films obtained after argon ions sputtering for 600 s

Table 2 Surface composition of Cr1-xAlxN films

Sample	Surface composition/at%				$\frac{{{C}_{\text{Al}}}}{({{C}_{Cr}}+{{C}_{\text{Al}}})}$	$\frac{{{C}_{\text{N}}}}{({{C}_{Cr}}+{{C}_{\text{Al}}})}$	Film composition (Cr_1-_xAl_xN_y)
Sample	Cr	Al	N	O	$\frac{{{C}_{\text{Al}}}}{({{C}_{Cr}}+{{C}_{\text{Al}}})}$	$\frac{{{C}_{\text{N}}}}{({{C}_{Cr}}+{{C}_{\text{Al}}})}$	Film composition (Cr_1-_xAl_xN_y)
CrAlN 1#	32.9	22.6	41.8	2.7	0.41	0.75	Cr_0.59Al_0.41N_0.75
CrAlN 2#	26.2	29.1	41.3	3.4	0.53	0.75	Cr_0.47Al_0.53N_0.75
CrAlN 3#	19.8	34.6	42.2	3.4	0.64	0.78	Cr_0.36Al_0.64N_0.78
CrAlN 4#	15.1	39.9	42.1	2.9	0.73	0.77	Cr_0.27Al_0.73N_0.77

Fig. 4 High resolution XPS spectra of Cr1-xAlxN films (a) Cr2p; (b) N1s; (c) Al2p

Fig. 5 XRD patterns of Cr1-xAlxN films

Fig. 6 Hardness (H), elastic modulus (E) and H/E* of Cr1-xAlxN films

Fig. 7 Typical load-displacement curves of Cr1-xAlxN films

Fig. 8 Frictional force vs normal force curves for Cr1-xAlxN films during scratch test

Fig. 9 Micrographs of scratch of Cr1-xAlxN films

Table 3 Critical load and CPRS of Cr1-xAlxN films

Sample	L_C1/N	L_C2/N	CPR_S
CrAlN 1#	75.4	83.8	633.36
CrAlN 2#	64.6	87.3	1466.42
CrAlN 3#	60.2	80.4	1216.14
CrAlN 4#	61.3	82.5	1299.56

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