Improving the Accuracy of Low-load Vickers Microhardness Testing of Hard Thin Films

AbstractExperiments that involved the testing of different steel samples over a wide range of loads were conducted in order to investigate the influence of micro-loads on accuracy of Vickers microindentation hardness testing. We found that for the same material the Vickers microhardness decreases with the decreasing of test load. The measuring error of Vickers microhardness on a steel block sample with known hardness was -25% when we used 10 gf load force. This is due to the fact that diagonal length values are in the range of micrometers and the precision of reading using optical microscopy is ± 0.5μm in length for most operators In order to improve accuracy of the reading of indents diagonals length we used two additional methods: scanning electron microscopy and graphical image processing. By this approach the measuring error of HV0.01 was reduced to an error of 3.78%.On samples coated with nanostructured (TiAlSi)N hard thin films developed by DC unbalanced magnetron sputtering, with thickness of 2..3μm, we found values around 2500 HV0.01 using this improved Vickers microhardness testing methodology

Novel Hierarchical Micro/Nano Modified Surfaces for Dental Implants

Present paper presents the modification at nano scale level of the surfaces of Ti6Al4V alloy that were previously modified at micro scale level by acid etching (AE) or by sand blasting with large grit and acid etching (SLA). Continuous, self-ordered nanostructured (nanoporous/nanotubular) oxide layers superimposed onto micro rough topographies were developed by using electrochemical anodization in fluoride based solutions, and optimized process parameters. Novel hierarchical micro/nano modified surfaces, with well developed oxide nanotubes of 40-110 nm in diameter, were synthesis by anodization in 1M H3PO4 + 0.4 wt% HF electrolyte, at anodization potential of 24 V, applied with a potential ramp of 0.08 V/s

Optimization of TiO

Titanium based modified surfaces with TiO2 self-organized nanotubular layers for biomedical applications were synthesized on cylindrical surfaces by electrochemical anodization in phosphate/fluoride electrolytes. Cylindrical samples of φ 3.8 x 20 mm, made of Ti6Al4V alloy, with different initial surface preparation (machined, grinded, polished) were subjected to anodization and process parameters were optimized to assure the development of uniform titania nanotubular layers with nanotubes’ diameter of 25-100 nm. Optimal process parameters in our custom-built anodization cell are: electrolyte composition 1M H3PO4 + 0.4 wt% HF, anodization potential U = 24 V, potential ramp Ur = 0.08 V/s, distance anode-cathode d = 15 mm, current density in potentiostatic stage J = 35-50 A/m2, and anodization duration t = 30-35 min

Optimized anodization setup for the growth of TiO2 nanotubes on flat surfaces of titanium based materials

An extensive research work on development of nanostructured TiO2 layers on the surface of titanium based materials for biomedical implants led the authors to the optimization of process parameters of electrochemical anodization in phosphate/fluoride based electrolytes. Based on those parameters, a dedicated optimized electrochemical anodization setup was originally designed and realized. The anodization bath was designed in order to provide a proper circulation of electrolyte and the possibility of distance anode-cathode modification, the DC power supply was designed accordingly to the electrical parameters requested by the nanotubes development, and a dedicated software (Nanosource) was developed for process control and ease and flexibility of process parameters acquisition, storage and processing

Influence of electrical parameters on morphology of nanostructured TiO2 layers developed by electrochemical anodization

Ti6Al4V alloy micro rough surfaces with TiO2 self-organized nanostructured layers were synthesized using electrochemical anodization in phosphate/fluoride electrolyte, at different end potentials (5V, 10V, 15V, and 20 V). The current – time characteristics were recorded, and the link between current evolution and the morphology of developing oxide layers was investigated. On flat surfaces of Ti6Al4V alloy we developed TiO2 layers with different morphologies (random pores, nanopores of 25…50 nm, and highly organized nanotubes of 50…100 nm in diameter) depending on electrical parameters of anodization process. In our anodization cell, in optimized conditions, we are able to superimpose nanostructured oxide layers (nanotubular or nanoporous) over micro structured surfaces of titanium based materials used for biomedical implants

Optimized anodization setup for the growth of TiO

An extensive research work on development of nanostructured TiO2 layers on the surface of titanium based materials for biomedical implants led the authors to the optimization of process parameters of electrochemical anodization in phosphate/fluoride based electrolytes. Based on those parameters, a dedicated optimized electrochemical anodization setup was originally designed and realized. The anodization bath was designed in order to provide a proper circulation of electrolyte and the possibility of distance anode-cathode modification, the DC power supply was designed accordingly to the electrical parameters requested by the nanotubes development, and a dedicated software (Nanosource) was developed for process control and ease and flexibility of process parameters acquisition, storage and processing