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Zinc (Zn) and its alloys have been proved to be promising candidate materials for biodegradable cardiovascular stents. In this study, a novel extruded Zn-0.02 Mg-0.02Cu alloy was prepared. Compared with pure Zn, the Zn-based alloy showed higher mechanical properties, and the Zn-based alloy could significantly accelerate Zn2+ release, reaching 0.61 ± 0.11 μg/mL at 15 days of immersion. In vitro biocompatibility studies demonstrated that the Zn-based alloy had excellent cytocompatibility and hemocompatibility, including low hemolysis rate (0.63 ± 0.12%) and strong inhibitory effect on platelet adhesion. Subsequently, the Zn-based alloy stent was implanted into the left carotid arteries of New Zealand white rabbits for 12 months. All the rabbits survived without any adverse clinical events, and all the stented arteries were patent during the study period. Rapid endothelialization at 1 week of implantation was observed, suggesting a low cytotoxicity and thrombosis risk. The stent corroded slowly and no obvious intimal hyperplasia was observed for 6 months, after which corrosion accelerated at 12 months. In addition, no obvious thrombosis and systemic toxicity during implantation period were observed, indicating its potential as the backbone of biodegradable cardiovascular stents. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1814-1823, 2019.

PurposeThe objectives of this paper are to assess the sliding wear response of a zinc‐based alloy over a range of sliding speeds and pressures in oil‐lubricated condition with respect to a cast iron, to understand the role of different microconstituents in controlling the observed wear behaviour and to examine various operating material removal mechanisms.Design/methodology/approachSliding wear tests have been carried out using a pin‐on‐disc machine in oil‐lubricated condition at different speeds and pressures. The wear response has been explained in terms of specific nature of various microconstituents of the specimen materials and substantiated through the characteristics of wear surfaces, subsurface regions and debris particles.FindingsThe wear rate increased with the sliding speed while load produced a mixed influence. Further, the friction coefficient and frictional heating were influenced by the test duration, load and speed in a mixed manner. Moreover, the zinc‐based alloy attained lower wear rate but higher friction coefficient than that of the cast iron while frictional heating followed a mixed trend.Practical implicationsThe paper further establishes a zinc‐based alloy as a potential substitute material system to a well‐known cast iron in tribological applications and enables further understanding of the wear mechanisms.Originality/valueThe present paper assesses the sliding wear performance of a lighter zinc‐based alloy as an effective potential substitute material system to cast iron in tribological applications. An attempt has also been made to understand the role played by different microconstituents in controlling the wear behavior and substantiate the wear response through the characteristics of wear surfaces, subsurface regions and debris.

This study pertains to the observations made during the sliding wear response of a zinc-based alloy in different test conditions. The effects of sliding speed and load on the wear behaviour of the alloy have been studied. The properties evaluated were wear rate, frictional heating and coefficient of friction. The wear performance of the zinc-based alloy has been compared with that of a conventional cast iron in identical test conditions. The wear rate of the samples increased with applied load and sliding speed while the seizure resistance (load) deteriorated with speed. The zinc-based alloy exhibited less wear rate and reduced frictional heating than that of the cast iron while friction coefficient followed a reverse trend. Observed wear response of the samples has been discussed in terms of specific features like lubricating, load carrying, microcracking and thermal stability of various microconstituents of the samples, and substantiated further through the features of wear surfaces, subsurface regions and debris.

This investigation presents the observations made pertaining to the lubricated sliding wear response of a zinc-based alloy containing nickel over a range of applied pressures and sliding speeds. Properties studied were wear rate and frictional heating. The varying wear response of the samples under different material and test conditions has been substantiated through the features of wear surfaces, subsurface regions, and debris. The role of various microconstituents in the material and their specific features have been correlated with the observed wear behaviour of the alloy in different material and test conditions. The wear rate and frictional heating increased with pressure and speed. The data plots in general comprised initially low slope followed by a higher slope at larger applied pressures. Heat-treated samples performed better than the as-cast one except at the maximum sliding speed; a reverse trend was noted in the latter case. The study suggests the benefits of heat treatment in terms of improved wear response of the alloy under specific test conditions. Moreover, the wear behaviour of the samples for different material and test conditions could be explained in terms of the features of their microconstituents and the predominance of one set of factors causing improved wear behaviour over the other producing a reverse effect.

Slurry wear characteristics of a zinc-based alloy composite containing 10 wt.% alumina particles have been analyzed by sample rotation technique in this study. The slurry comprised 0.4 g sodium chloride and 0.5 cm3 concentrated sulphuric acid dissolved in one litre of water plus varying concentration (up to 60 wt.%) of sand particles. The traversal distance was varied in the range of 15–500 km while test speeds were maintained at 4.71 and 7.02 m/s. It was observed that the wear response of the composite was influenced by parameters such as traversal speed and distance and the content of the sand particles in the environment. Wear rate reduced with increasing speed when tests were conducted in the liquid-only medium while the trend tended to reverse in the presence of the suspended sand particles in the medium. Further, the wear rate increased initially with distance, attained a peak and decreased thereafter at longer traversal distances. Testing the samples in the environment without sand led to higher wear rate when compared with the ones in the media containing sand. Further, within the liquid plus sand media, intermediate sand content (in the test environment) caused maximum wear rate. In this case, the maximum sand content exhibited minimum wear rate. The wear behaviour of the composite under varying conditions has further been substantiated through the characteristic features of the affected surfaces and subsurface regions. Operating wear mechanisms have been observed to be corrosion assisted erosion and abrasion. The predominance of one mechanism over the other(s) actually controlled the wear response of the composite in specific conditions of wear.

An attempt has been made in this investigation to assess the wear behavior of a zinc-based alloy in slurry. The influence of the sand content of the slurry and traversal speed and distance on the wear response of the alloy has been examined. Tests were also conducted in the liquid-only medium to assess the role played by the suspended sand particles in the medium. Testing the samples in the liquid-only medium (i.e., without sand particles) caused maximum wear rate. It was also observed that an intermediate sand concentration in the liquid exists wherein the samples experienced maximum wear rate (although less than in the liquid-only medium). Further, increasing the speed of rotation of the specimens in the liquid plus sand environments led to higher wear rate while the trend tended to reverse in the sand-free liquid environment. The alloy initially displayed increased wear rate with increasing traversal distance. This was followed by the attainment of the maximum, a decrease in the wear rate and then a steady state value at longer traversal distances. Wear behavior of the alloy under different experimental conditions was further substantiated through the features of the affected wear surfaces and subsurface regions (perpendicular below the affected surfaces).

This study discusses the sliding wear response of a zinc-based alloy (conforming to ZA 27) in mixed lubrication conditions at different sliding pressures and speeds. A conventional bearing bronze (conforming to SAE 660) was also tested under identical test conditions for comparison purposes.Wear rate increased with speed and pressure. Further, the zinc-based alloy attained superior wear response (less wear rate and frictional heating) than the bronze at all test speeds except prior to seizure (occurring at 7.0 MPa) at the speed of 4.60 m/s. The trend reversed in the latter case. Wear rate of the specimens also agreed with the degree of frictional heating experienced by them. A higher wear rate corresponded to larger frictional heating and vice versa. Wear behaviour of the samples improved considerably in the present study due to the presence of the oil lubricant as compared to the study in dry conditions.Wear behaviour of the samples has been discussed in terms of the nature and response of their ...

The present paper deals with the dry sliding wear behaviour of a zinc-based alloy against a stainless steel (grade 304) disc (counterface). The performance of the zinc-based alloy has been compared with that of a conventionally used leaded-tin bronze under identical test conditions. Wear tests have been conducted over a range of pressure and speed. The results revealed that the zinc-based alloy performs better than the bronze over the entire range of speed and pressure. Further, the bronze attained improved wear response at the higher sliding speed. At the lower speed, material chipping off caused the tests to be stopped beyond a specific pressure in the case of the bronze, while material seizure was observed at the higher speed. The zinc-based alloy attained comparable wear rates at both the speeds, while seizure pressure reduced at the higher speed.