Using IF unbalanced magnetron sputtering ion plating technology to make TiAlN thin film on a cemented carbide substrate YG6. The XRD, EDS, stereomicroscope, microhardness tester, and multi-functional surface property tester were used to study the structure and properties of the composites. The results show that when the target power is low, the film layer exists in the form of TiN and TiC. The preferential orientation surface (111) and microhardness of TiN are related to the bias voltage. When the target power is high, the film mainly contains Ti3AlN and AlN phases. The Ti3AlN phase is preferentially oriented along the (220) plane, the film structure is dense and uniform, and the ratio of N atoms to metal atoms is close to 1:1, the thickness of the film is 1.93 μm, the microhardness is 3145HV and the bonding force is 85N.
With the development of materials science, the application of thin film materials has become more and more extensive. TiAlN film is a new type of multi-element thin film coating material that has been successfully developed in recent years. It has excellent properties such as high hardness, high oxidation temperature, good thermal stability, strong adhesion, low friction coefficient, low thermal conductivity, etc. It is widely used in the tool industry, especially for efficient cutting of various difficult-to-machine materials. Also, TiAlN is expected to partially or completely replace TiN coatings. In this paper, TiAlN thin films were prepared on hard alloy YG6 by medium frequency magnetron sputtering technology. The phase structure, surface and fracture morphology, the composition and main properties of the thin films were measured by XRD, SEM, EDS, stereo microscope, microhardness tester and scratch tester..
1. Test Materials and Methods
1.1. Test materials
YG6 cemented carbide is selected as a substrate sample, pure Ti target and Al target (purity is 99.99%) are used as cathode targets. The working gas is argon (purity > 99.999%), and the reaction gas is nitrogen (purity > 99.999%).
The phase structure of the film is analyzed by DX-1000 X-ray diffraction analyzer, the surface of the film is observed by S-3400N scanning mirror, the hardness of the film is tested by HVS-1000 digital microhardness tester, and the film-based bonding force of the film is tested by the MFT-4000 material surface performance tester.
1.2. Preparation of TiAlN Films
The substrate samples are cleaned in an ultrasonic machine to remove grease, dust and oxide films, and then dried after dehydrating with alcohol. Pumping the vacuum to 6.7×10-3 Pa and heating to 500°C. Then begin to make coatings after cleaning the substrate with 1000 V high-pressure argon ion. Firstly, deposit a TiN transition layer. Next, deposit and prepare a TiAlN film with the nitrogen partial pressure is 0.3×10-1 Pa. Table 1 shows deposition process parameters for making TiAlN thin films.
Table 1. Deposition parameters of TiAlN film
Etch pulse bias/
The TiAlN thin film was successfully prepared on the cemented carbide substrate by medium frequency magnetron sputtering technology, and its phase structure, morphology and main properties were analyzed. The conclusions are as follows:
(1) XRD analysis results show that the film mainly exists in the form of TiN and TiC at the low Al target power, and the preferred orientation plane of TiN is (111). The TiC phase is caused by the partial substitution of C atoms in substrate for N atoms in TiN. The film layer mainly exists in the form of Ti3AlN and AlN under high Al target power, the Ti3AlN phase is preferentially oriented along the (220) crystal plane, the AlN phase is preferentially oriented along the (002) crystal plane, and the peaks of the two phases have different degrees of broadening and shift. This is mainly due to lattice distortions that caused by partial replacement of the Al atoms in AiN by Ti atoms.
(2) The fracture morphology analysis results show that the film is tightly bonded with the substrate, the film structure is dense and uniform, and there is a clear interface with the matrix phase. As the Al target power increases, the number of particles and sputtering energy increase, so the deposition rate increases, the thickness of the film increases, and the film thickness can reach 1.93 μm.
(3) EDS surface composition analysis results show that with the increase of Al target power, the crystallinity of the film increases, the Al content in the film layer is increases while the Ti content is decreases. The main component of the film layer is a metal nitride whose ratio of N atoms to metal atoms is close to 1:1.
(4) The microhardness test showed that at the low Al target power, the microhardness of the film increases first and then decreases with the increase of negative bias of the substrate, and the microhardness reaches 2391 HV. At high Al target power, the microhardness of the film can reach 3145 HV, which is mainly due to the lattice distortion caused by the formation of Ti3AlN hard phase and Ti atoms replacing Al atoms in AlN. The binding force test shows that the bonding force can reach 85 N, because the formation of hard phase of TiN-deposited transition layer and Ti3AlN, and the application of DC superimposed pulsed bias technology refine the grain and reduce the film lamination stress to improve membrane-based binding force.