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Open Access Research Article Issue
Wear mechanism and debris analysis of PEEK as an alternative to CoCrMo in the femoral component of total knee replacement
Friction 2023, 11 (10): 1845-1861
Published: 02 March 2023
Downloads:12

The polyetheretherketone (PEEK)-highly cross-linked polyethylene (XLPE), all-polymer knee prosthesis has excellent prospects for replacing the traditional metal/ceramic-polyethylene joint prosthesis, improving the service life of the joint prosthesis and the quality of patients’ life. The long-term wear mechanism of PEEK-XLPE knee joint prosthesis is comprehensively evaluated from wear amount, wear morphology, and wear debris compared to that of CoCrMo-XLPE joint prosthesis. After 5 million cycles of in vitro wear, the wear loss of XLPE in PEEK-XLPE (30.9±3.2 mg) is lower than that of XLPE in CoCrMo-XLPE (32.1±3.1 mg). Compared to the XLPE in CoCrMo-XLPE, the plastic deformation of XLPE in PEEK-XLPE is more severe in the early stage, and the adhesive peeling and adhesion are lighter in the later stage. The size distribution of XLPE wear debris in PEEK-XLPE is relatively dispersed, which in CoCrMo-XLPE is relatively concentrated. Wear debris is mainly flake and block debris, and the wear mechanism of XLPE was abrasive wear. The wear volume per unit area of PEEK femoral condyle (10.45×105 μm3/mm2) is higher than that of CoCrMo (8.32×105 μm3/mm2). The PEEK surface is mainly furrows and adhesions, while the CoCrMo surface is mainly furrows and corrosion spots. The PEEK wear debris is mainly in flakes and blocks, and the CoCrMo wear debris is mainly in the shape of rods and blocks. The wear mechanism of PEEK is abrasive wear and adhesion, and that of CoCrMo is abrasive wear and corrosion.

Open Access Research Article Issue
Cartilage-bone inspired the construction of soft-hard composite material with excellent interfacial binding performance and low friction for artificial joints
Friction 2023, 11 (7): 1177-1193
Published: 16 July 2022
Downloads:26

Inspired by the cartilage-bone structure in natural joints, soft-hard integrated materials have received extensive attention, which are the most promising candidates for artificial joints due to their combination of excellent load-bearing properties and lubricating properties. The latest progress showed that the combination of hydrogel and titanium alloy can realize a bionic natural joint lubrication system on the surface of titanium alloy. However, obtaining a tough interface between the hydrogel (soft and wet) and the titanium substrate (hard and dry) is still a great challenge. Here, we designed a "soft (hydrogel)-hard (Ti6Al4V)" integrated material with outstanding combination, which simulates the structure and function of cartilage-bone in the natural joint. The load-bearing properties, binding performance, and tribological behaviors for different forms of the soft-hard integrated materials were investigated. The results showed that the hydrogel layer and Ti6Al4V substrate possess ultra-high interfacial toughness (3,900 J/m2). In addition, the combination of the hydrogel layer and Ti6Al4V substrate provided a good lubrication system to endow the "soft (hydrogel)-hard (Ti6Al4V)" integrated material with high load-bearing and excellent tribological properties. Therefore, this study provided an effective strategy for prolonging the service life of Ti6Al4V in the biomedical field.

Open Access Research Article Issue
Microscopic dynamic observation of adhesion hysteresis friction and exploration of the influence of different pressures on friction transmission
Friction 2021, 9 (4): 758-773
Published: 04 June 2020
Downloads:28

The mechanism of adhesive friction between viscoelastic materials is a key question. In this study, the friction process of the adhesive interface between a friction lining and a wire rope is dynamically observed in real time to analyze the adhesion hysteresis friction intuitively and quantitatively. The adhesion is determined by the state of motion, while the relative displacement of the wire rope and lining is used to find the magnitude of the adhesive friction. The hysteresis friction is reflected by the internal deformation of the lining. The magnitude of the hysteresis friction is determined by the displacement difference (Δx) in the sliding direction of two marked points at different distances from the contact surface. The results show that the adhesion friction is proportional to the loss modulus and the hysteresis friction is proportional to the ratio of the loss modulus to the square of the storage modulus (E"/(E'2)). The frictional vibration first decreases and then increases with the increase in pressure. The K25 lining has the highest adhesion hysteresis friction and minimal frictional vibration. The result provides a simple and intuitive method for research into the friction transmission and vibration of viscoelastic materials.

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