Wear Rate, Tribo-Corrosion, and Plastic Deformation Values of Co-Cr-Mo Alloy in Ringer Lactate Solution.

This study investigates the tribocorrosion performance of a cast Co-Cr-Mo alloy prepared using casting and electromagnetic stirring (EMS) at specific frequencies. The tribocorrosion behaviour of the alloy was evaluated when exposed to Ringer's lactate solution to optimize the EMS parameters and improve its properties. The research focuses on biomedical implant applications and explores how EMS affects alloy wear and corrosion resistance. As did the friction coefficient and wear volume, the wear rate of samples produced with EMS frequencies of 75 Hz and 150 Hz decreased. These improvements are attributed to the ability of EMS to refine grain size and homogenize the microstructure, thereby increasing the resistance to tribocorrosion. Techniques such as scanning electron microscopy (SEM) and profilometry were used for surface and wear analysis, while mechanical properties were evaluated through instrumented indentation tests. The findings confirm that EMS improves the alloy's durability and tribocorrosion resistance, making it highly suitable for demanding biomedical applications such as joint replacements. This highlights the importance of advanced manufacturing techniques in optimizing biomedical alloys for simulated body conditions.

Effect of DLC Films with and without Silver Nanoparticles Deposited On Titanium Alloy.

Diamond-like carbon (DLC) film is a biocompatible hard coating material that can prevent the leaching of metal ions. This study evaluates the structural characteristics of DLC, with and without silver nanoparticles, deposited by plasma (PECVD) on titanium alloy (Ti-6Al-4V) and bone formation in contact with DLC films. Sixty Ti-6Al-4V samples were used divided in: uncoated, coated with DLC and coated with DLC-Ag. After structural characterization, samples were fixed bilaterally at the rabbit's mandible. After 15 and 90 days, samples were characterized again and bone formation in the area was analyzed by histomorphometry. Statistical analysis was performed by two-way ANOVA. Both the DLC and DLC-Ag films were firmly adhered and showed a high electrical resistance without significant changes in the Raman spectrum after in vivo integration. After 15 days, there were immature bone trabeculae in the interface and partially covering the surface. After 90 days, mature bone filled the interface and coved the surface. There was no statistically significant difference among the three groups in both periods. In conclusion, osseointegration with DLC, DLC-Ag and uncoated Ti-6Al-4V is similar. However, DLC and DLC-Ag coverings have the advantage of electrical insulation and can presumably control bacterial activity and ion leaching.

Flexible camphor diamond-like carbon coating on polyurethane to prevent Candida albicans biofilm growth.

Camphor was incorporated in diamond-like carbon (DLC) films to prevent the Candida albicans yeasts fouling on polyurethane substrates, which is a material commonly used for catheter manufacturing. The camphor:DLC and DLC film for this investigation was produced by plasma enhanced chemical vapor deposition (PECVD), using an apparatus based on the flash evaporation of organic liquid (hexane) containing diluted camphor for camphor:DLC and hexane/methane, mixture for DLC films. The film was deposited at a low temperature of less than 25°C. We obtained very adherent camphor:DLC and DLC films that accompanied the substrate flexibility without delamination. The adherence of camphor:DLC and DLC films on polyurethane segments were evaluated by scratching test and bending polyurethane segments at 180°. The polyurethane samples, with and without camphor:DLC and DLC films were characterized by Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and optical profilometry. Candida albicans biofilm formation on polyurethane, with and without camphor:DLC and DLC, was assessed. The camphor:DLC and DLC films reduced the biofilm growth by 99.0% and 91.0% of Candida albicans, respectively, compared to bare polyurethane. These results open the doors to studies of functionalized DLC coatings with biofilm inhibition properties used in the production of catheters or other biomedical applications.

Macrophages adhesion rate on Ti-6Al-4V substrates: polishing and DLC coating effects

Abstract Introduction Various works have shown that diamond-like carbon (DLC) coatings are able to improve the cells adhesion on prosthesis material and also cause protection against the physical wear. On the other hand there are reports about the effect of substrate polishing, in evidence of that roughness can enhance cell adhesion. In order to compare and quantify the joint effects of both factors, i.e, polishing and DLC coating, a commonly prosthesis material, the Ti-6Al-4V alloy, was used as raw material for substrates in our studies of macrophage cell adhesion rate on rough and polished samples, coated and uncoated with DLC. Methods The films were produced by PECVD technique on Ti-6Al-4V substrates and characterized by optical profilometry, scanning electron microscopy and Raman spectroscopy. The amount of cells was measured by particle analysis in IMAGE J software. Cytotoxicity tests were also carried out to infer the biocompatibility of the samples. Results The results showed that higher the surface roughness of the alloy, higher are the cells fixing on the samples surface, moreover group of samples with DLC favored the cell adhesion more than their respective uncoated groups. The cytotoxity tests confirmed that all samples were biocompatible independently of being polished or coated with DLC. Conclusion From the observed results, it was found that the rougher substrate coated with DLC showed a higher cell adhesion than the polished samples, either coated or uncoated with the film. It is concluded that the roughness of the Ti-6Al-4V alloy and the DLC coating act complementary to enhance cell adhesion.

Deposition of hard and adherent diamond-like carbon films inside steel tubes using a pulsed-DC discharge.

A new, low cost, pulsed-DC plasma-enhanced chemical vapor deposition system that uses a bipolar, pulsed power supply was designed and tested to evaluate its capacity to produce quality diamond-like carbon films on the inner surface of steel tubes. The main focus of the study was to attain films with low friction coefficients, low total stress, a high degree of hardness, and very good adherence to the inner surface of long metallic tubes at a reasonable growth rate. In order to enhance the diamond-like carbon coating adhesion to metallic surfaces, four steps were used: (1) argon ion sputtering; (2) plasma nitriding; (3) a thin amorphous silicon interlayer deposition, using silane as the precursor gas; and (4) diamond-like carbon film deposition using methane atmosphere. This paper presents various test results as functions of the methane gas pressure and of the coaxial metal anode diameter, where the pulsed-DC voltage constant is kept constant. The influence of the coaxial metal anode diameter and of the methane gas pressure is also demonstrated. The results obtained showed the possibilities of using these DLC coatings for reduced friction and to harden inner surface of the steel tubes.