PTFE has excellent chemical stability and good self-lubrication, it is the most excellent artificial solid friction reduction material, its tribological properties are closest to human cartilage tissue, therefore, coating PTFE on the surface of Ti alloy will greatly improve the sliding friction performance of Ti alloy. However, PTFE itself has low strength, extremely low surface energy, and poor affinity with metal, so the direct coating of PTFE on the surface of Ti alloy has low bonding strength and is easy to peel off.
Based on the above reasons, this paper will utilize chemically plated Ni-P as the substrate to support PTFE particles. Ni-P-PTFE composite coating is deposited on the surface of Ti alloy to obtain a surface modified layer with self-lubrication and low friction factor on the surface of Ti alloy, and the friction and wear properties of Ni-P-PTFE are investigated.
2 Process
Ti-6Al-4V can be chemically plated with Ni-P-PTFE after pre-treatment such as degreasing, removing oxidized film, and activation, etc. Chemical plating of Ni-P-PTFE requires that the particles of PTFE can be dispersed uniformly in the solution. In this experiment, PTFE particles with a particle size of about 0.05-0.5 μm were used. An appropriate amount of PTFE particles was added to the acidic chemical nickel plating solution [4] and mechanically stirred. The process conditions for chemical plating of Ni-P-PTFE were as follows: NiSO4-6H2O: 25 g/L; NaH2PO2-H2O: 27 g/L citric acid: 20 g/L; sodium acetate: 20 g/L; accelerator: 2 g/L; stabilizer: 5×10-2 g/L; surfactant: 10 ml/L; pH 4.6-5.0; and the temperature was 85 ℃. The added surfactant was a mixture of nonionic surfactant and cationic surfactant, which not only provided good suspension of PTFE particles in the plating solution, but also made the PTFE particles positively charged, which promoted the adsorption of PTFE particles on the surface of Ti-6Al-4V and **** deposition with Ni-P [5]. The volume content of PTFE in the obtained Ni-P-PTFE composite layer reaches 10% to 15%, and the coating has a gray metallic luster. Using SEM to observe the plating layer found that PTFE particles in the plating layer distribution is more uniform, the plating layer is flat and no pores.
3 Friction performance of the coating
The friction wear test was carried out on MM-200 wear tester with GCr15 coupling, radius 23.5 cm, load 50 N and sliding speed 1 m/sec. The test was carried out under dry friction conditions.
Ni-P-PTFE shows high abrasion resistance, and its wear amount reaches a stable value in a relatively short period of time, and then shows a decreasing trend with the increase of wear time. Figure 1 shows the relationship between friction factor and wear time. From the figure, it can be seen that the friction factor of Ni-P-PTFE is very low and has a good friction reduction effect, and its wear factor remains basically unchanged with the increase of the sliding distance, and the fluctuation of the friction factor is very small.The friction and wear performance of Ti-6Al-4V alloy is significantly improved after chemical plating Ni-P-PTFE treatment.
Fig 1 Coefficient of friction with wear time
Fig 1 Coefficient of friction with wear time
4 CONCLUSION
(1) The chemical composite plating process can be used to obtain Ni-P-PTFE composite plating layer on the surface of Ti-6Al-4V, which PTFE content is in the range of 10-15 vol%, and the plating layer is smooth and dense.
(2) The chemically plated Ni-P-PTFE composite layer has excellent wear resistance and friction reduction, which greatly improves the friction and wear performance of Ti-6Al-4V, making it possible to apply Ti-6Al-4V in artificial joints and other parts with high wear.
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Dongguan Yingcheng Teflon Co.
Contact: Gao Baocheng Business Manager
Telephone: 0769-83841809 (to contact) The enterprise please call this number)
Location: Dongguan, Guangdong Province
Contact Address: Zhangmutou Town, Dongguan City, Zhangluo Longzhu two blocks
Teflon (PTFE) due to the possession of a strong carbon a fluorine bond and high molecular weight so that it has the following excellent characteristics:
● Wide range of temperature: -200 ℃ ~ +260 ℃
● Resistant to chemicals that can corrode under pressure
● Anti-adhesive properties
● Extremely low coefficient of friction
● Non-combustible
● Excellent gas properties (does not change with frequency and temperature)
● Excellent mechanical properties
● Shock-resistant and elasticity resistant
● No aging problems
● Resistant to moisture and ultraviolet rays
● No aging problems
. ● Resistant to moisture and UV rays
● Non-toxicity
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