Comparative Analysis Over Tribology Characterization of TiAlN and TiAlSiN PVD Coating On Plasma Nitride Alloy 20

The nickel-iron-chromium (alloy 20) is enriching by hybrid surface treatment through plasma nitride (PN) and physical vapor deposition (PVD) process. The plasma nitriding process takes 12 hours at 500°C. Potentiodynamic testing is used to characterize the corrosion performance of the treated material, followed by morphological analysis of the exposed surface; XRD, EDX, SEM, hardness, and tensile testing are used to investigate appropriate coating properties. Plasma nitride and hybrid PVD nickel-iron-chromium alloys exhibit perlite (γ + α ’) phases and martensite (γ + α) phases, respectively. The martensite microstructure ensures superior tensile strength and hardness. The pin-on-disc tribometer test proposes to analyze friction and hard-faced behavior in the dry sliding position. The inclusion of Si improves the adherent oxide film, resulting in a low wear rate in TiAlSiN alloy 20. Due to the presence of the passive film, TiAlSiN alloy 20 exposes the most passive region to attain better corrosion resistance.

MODERN MATERIALS FOR IMPLANTS USED IN THE TREATMENT OF DOGS WITH WOBBLER SYNDROME

Wobbler's syndrome or caudal cervical spondylomyelopathy is a disease of the cervical spine in dogs of large and giant breeds, characterized by dynamic or static compression of the cervical spinal cord and nerve roots, which leads to neurological deficits and neck pain. Currently, there are many materials for the manufacture of various implants, as well as prosthetic discs, which are successfully used in the treatment of dogs with Wobbler syndrome, but veterinary neurologists have certain dissatisfaction with the results of surgical treatment, as a result of which a number of postoperative complications are noted. This makes it necessary to use new materials for the manufacture of implants. Currently, the vast majority of veterinary specialists use only titanium and stainless steel alloys (304V and 316LVM) as a material for cages, screws and plates. However, a number of shortcomings of these materials indicate the need for a search new innovative materials with improved characteristics. Currently, the materials used for the manufacture of implants in human medicine are of great interest, but have not yet found application in veterinary medicine (with the exception of stainless steel and titanium alloys). Among such materials are polyether etherketone (PEEK), carbon fiber reinforced polyether etherketone (CFR-PEEK), cobalt-chromium alloys, nitinol, tantalum. The article reflects the characteristics of these materials for the manufacture of implants, their advantages and disadvantages.

Optimization of the Manufacturing Process by Molding Cobalt-Chrome Alloys in Assembled Dental Frameworks

In oral rehabilitation, the treatment of partial edentulism (PEd) is performed by removable partial dentures (RPD) or assembled prosthetic works (APW) composed of several components, fixed to the prosthetic field (Pa) and a removable one (Pb), in order to facilitate the daily hygiene but also the damping of the occlusal forces applied in mastication. Cobalt-Chromium alloys are materials used to manufacture modern prosthetic assembles. In order for this study to be relevant, it was necessary to standardize the design of the framework (Pa) in terms of shape and volume so that the experiment could be reproducible for the five Co-Cr alloys: 0-A (Co-Cr-Mo), 5-A and 10-A (Co-Cr-Mo-W), 15-A and 16.4-A (Co-Cr-W-Fe) and for the three fabrication methods of dental assembled prosthetic frameworks: refractory duplicate method (RD) resulting removable framework (Pb), direct construction method (DC) resulting removable framework (Pb-) and casting over metal method (CoM) resulting removable framework (Pb+). The time allocated to the adaptation process (AP), mechanical processing and sandblasting, in order to assemble the two components was between 43–70 min, even though the assembly between the Pa-framework and the complementary framework (Pb+) was not necessary, CoM-method hs been provide the elimination of AP step. By applying the arithmetic simple rule of three, the percentages for each of the three methods used were calculated, the values of the difference were obtained. The CoM method improves the joining precision between the components of the removable assembly of prosthetic frameworks by 91.7% compared to the RD method and by 80.62% compared to the DC method. According to the efficiency of the methods used in the precision of joining between frameworks components, their order is: casting over metal, direct construction and refractory duplicate method.

Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches

Titanium (Ti) alloys have been proven to be one of the most suitable materials for orthopaedic implants. Dual modular stems have been introduced to primary total hip arthroplasty (THA) to enable better control of the femoral offset, leg length, and hip stability. This systematic review highlights information acquired for dual modular Ti stem complications published in the last 12 years and offers a conclusive discussion of the gathered knowledge. Articles referring to dual modular stem usage, survivorship, and complications in English were searched from 2009 to the present day. A qualitative synthesis of literature was carried out, excluding articles referring solely to other types of junctions or problems with cobalt-chromium alloys in detail. In total, 515 records were identified through database searching and 78 journal articles or conference proceedings were found. The reasons for a modular neck fracture of a Ti alloy are multifactorial. Even though dual modular stems have not shown any clinical benefits for patients and have been associated with worse results regarding durability than monolithic stems, some designs are still marketed worldwide. Orthopaedic surgeons should use Ti6Al4V dual modular stem designs for primary THA in special cases only.

Study of the Impact of Protective Process Agents with Carbon Nanopowder Additives on Chip Forming Processes

The present study describes the impact of various protective process agents on chip forming processes. The research was conducted on NiCr20TiAl and 34NiCrMoV14-5 nickel-chromium alloys. New lubricant-cooling process agents with carbon nanopowder additives are studied. The optimal composition of the nanopowder additive and its effect during alloy cutting is examined. Experiments reveal the dependence of shrinkage ratio on cutting speed and various protective process agents. The values of H50 microhardness are also defined when cutting these alloys using protective process agents. Experimental studies found the positive effect of developed agents with nanopowder additives on the processes of NiCr20TiAl and 34NiCrMoV14-5 alloys chip formation.