Brandusa Ghiban

Mechanical and Corrosion Behaviour of Some Devices for Ostheosinthesis

Orthopaedic implants represent mechanical devices which may be used for different purposes in human skeleton. such as either repairing of soft tissues (ligaments) or hard tissues (fractures. osteotomy. partial or total replacements). The aim of present paper is to put in evidence some macro and micro structural features revealed at state of surface after 5 months of implant in a female femoral fracture. Investigated surfaces were analyzed by optical and scanning electron microscopy and by X-Rays diffraction.

Silicon Influence on Corrosion Properties of Austenitic Stainless Steels

In the present paper there are presented results concerning comparative corrosion resistance of some austenitic stainless steels, with or without silicon content. The silicon content is varying in the range of 1-5 %, in a matrix of alloyed austenite, containing 20% Cr and 15-18%Ni and with very low carbon contents (lower than 0,03% C). There are investigated different types of corrosion resistance: intergranular corrosion in nitrogen media, stress corrosion resistance in chloride media, and transpassive behaviour in sulphuric media. The testing media contained nitrogen, as it follows: Huey test (65% HNO3, at boiling temperature, 244 hours maintain), and 5N HNO3 +1g/l Cr6+ (144 h, at boiling temperature). The media containing chloride is 45% MgCl2 at boiling temperature, with a period of 1000 hours. The transpassive behaviour is tested in 10% HSO4. The investigations were made by optic and electronic microscope, and the corroded surfaces were examined by scanning electron microscopy.

Surface Energies Acting at the Interfaces of Ceramics and Glasses while in Contact with Organic and Biological Liquids

The surface energy components which govern the interfacial interactions between bioinert solid substrates of partial stabilized ZrO2 (with 3 mol% Y2O3) and a glass with a composition of 55SiO2×10Na2O×35MgO in contact with organic and biological liquids under equilibrium regime, were determined. The experimental results indicated that the interfacial bonding between zirconia and the polar liquids is result of interactions due to dispersion forces. In the case of the glass, polar forces significantly contribute to solid/liquid interfacial interactions.

Cobalt Based Alloys for Dental Applications

The present paper put in evidence the mechanical behaviour of some commercial dental cobalt alloys, after own classification. The experimental cobalt alloys were classified in according either with molybdenum content, or with Cr+Mo content. A hierarcy of the alloys was finally made. The fractographic surfaces were investigate both by stereomacroscopy and scanning electron microscopy, putting in evidence the main structural features.

Failure Modes of the Biometallic Materials - Case Study

Hip fractures/arthrosis were, still are and will be a challenge for the orthopedic surgeon. In this paper we conducted a case study on a rod used for hip replacement due to coxartrosis. The implant was used for hip replacement for NC patient aged 82 years. After twelve months the patient returns for the ablation of osteosynthesis material. Clinical and strengthen the fracture hip is found radiologic hypertrophic and degradation plaque. It was used a rod implant, on which were made following investigations in order to establish the causes that led to the fracture, namely: determining the chemical composition through spectral analysis, analysis macrostructural in stereo, microstructural analysis optical microscope metallographic respectively analysis fractogr aphic electron microscope streak. Complex analysis of the fracture surfaces of the hip prosthesis has led to the ultimate conclusion that the material has been made the hip prosthesis is inadequate chemical purity satisfactory embedding, which has led to breakage within an area of non-homogeneous structure.

Surface Characterization of Some CoCrMo Dental Alloys

The removable partial dentures are made of alloys from CoCrMo system. This survey work paper considers various commercial CoCrMo alloys that were investigated in terms of surface behavior through different processing methods, respectively: sand blasting, grinding, milling, smoothing and polishing, procedures applied in accordance with the necessary standards for prostheses processing in dental labors, regarding their final trimming. Alloys behavior highlighting was performed by macrostructural investigations carried out at stereomicroscope. In the end an alloy hierarchy was achieved according to the method in which the main macrostructural aspects were highlighted.