Properties of TiO2 coatings applied by atomic layer deposition (ALD) on 100Cr6 steel

The paper presents the method of forming TiO2 coatings on 100Cr6 steel using the ALD method and assessing the properties of the obtained coatings. The coatings were assessed in terms of surface morphology, chemical composition, contact angle and tribological properties. The performed tribological tests show that TiO2 coatings are characterized by lower resistance to motion. During measuring the geometric structure of surfaces on samples with TiO2 coating, smaller wear traces were recorded than for 100Cr6 steel. The obtained values of the contact angles prove that the 100Cr6 steel coated with TiO2 is more hydrophobic than the uncoated 100Cr6 steel. TiO2 coatings can be used in low-loaded tribological systems and as barrier coatings

Properties of TiO2 coatings applied by atomic layer deposition (ALD) on 100Cr6 steel

The paper presents the method of forming TiO2 coatings on 100Cr6 steel using the ALD method and assessing the properties of the obtained coatings. The coatings were assessed in terms of surface morphology, chemical composition, contact angle and tribological properties. The performed tribological tests show that TiO2 coatings are characterized by lower resistance to motion. During measuring the geometric structure of surfaces on samples with TiO2 coating, smaller wear traces were recorded than for 100Cr6 steel. The obtained values of the contact angles prove that the 100Cr6 steel coated with TiO2 is more hydrophobic than the uncoated 100Cr6 steel. TiO2 coatings can be used in low-loaded tribological systems and as barrier coatings

Influence of surface roughness on selected properties of the TiAlN coating

The HS6-5-2C steel samples with different surface roughness were used for the tests. After grinding had a roughness parameter of Ra = 0,03 μm, and after polishing Ra = 0,01 μm. A TiAlN coating was applied to the substrate prepared in this way. Using a confocal microscope with an interferometric mode, the geometrical structure of the samples was analyzed. The optical strain gauge was used to measure the contact angle. Tribological tests were carried out in conditions of technically dry friction. The polished sample with the coating was characterized by a more stable course of the friction coefficient, lower wear and a smaller wetting angle

Influence of surface roughness on selected properties of the TiAlN coating

The HS6-5-2C steel samples with different surface roughness were used for the tests. After grinding had a roughness parameter of Ra = 0,03 μm, and after polishing Ra = 0,01 μm. A TiAlN coating was applied to the substrate prepared in this way. Using a confocal microscope with an interferometric mode, the geometrical structure of the samples was analyzed. The optical strain gauge was used to measure the contact angle. Tribological tests were carried out in conditions of technically dry friction. The polished sample with the coating was characterized by a more stable course of the friction coefficient, lower wear and a smaller wetting angle

The influence of environmental conditions on the tribological properties of the Ti13Nb13Zr alloy

The paper presents the results of tribological tests of the Ti13Nb13Zr titanium alloy - carried out in the conditions of lubrication with liquids simulating body fluids. Artificial saliva solutions were used for the tests. Two pH values were used – 7,0 characteristic of a healthy organism and 4,9 - typical for the presence of inflammation. The countersample in the tested friction nodes were Al2O3 balls with a diameter of 6 mm loaded with a normal force of 1 N. The tests obtained showed a strong influence of environmental conditions on the tribological properties of the Ti13Nb13Zr titanium alloy. This applies to both the value of the coefficient of friction and linear wear. In the case of tests carried out under lubrication conditions with an artificial saliva solution at pH 7,0 they were 0,47 and 31,1 μm, respectively; in the case of a fluid at pH 4,9 they were 25 % and 45 % higher (0,62 and 65,6 μm)

The influence of environmental conditions on the tribological properties of the Ti13Nb13Zr alloy

The paper presents the results of tribological tests of the Ti13Nb13Zr titanium alloy - carried out in the conditions of lubrication with liquids simulating body fluids. Artificial saliva solutions were used for the tests. Two pH values were used – 7,0 characteristic of a healthy organism and 4,9 - typical for the presence of inflammation. The countersample in the tested friction nodes were Al2O3 balls with a diameter of 6 mm loaded with a normal force of 1 N. The tests obtained showed a strong influence of environmental conditions on the tribological properties of the Ti13Nb13Zr titanium alloy. This applies to both the value of the coefficient of friction and linear wear. In the case of tests carried out under lubrication conditions with an artificial saliva solution at pH 7,0 they were 0,47 and 31,1 μm, respectively; in the case of a fluid at pH 4,9 they were 25 % and 45 % higher (0,62 and 65,6 μm)

Weighted Radon transforms for which the Chang approximate inversion formula is precise

We describe all weighted Radon transforms on the plane for which the Chang approximate inversion formula is precise. Some subsequent results, including the Cormack type inversion for these transforms, are also given

Control de la demanda laboral e hipertensión: estudio transversal en mecanógrafo colombiano

Introduction Hypertension has become a public health a worldwide challenge. It has been associated with psychosocial working conditions and with several chronic diseases. One of the job positions where poor psychosocial working condition might be present is a typist. We aimed to determine the prevalence of hypertension In Colombian typist population, associated with psychosocial factors at the work and identifying associated socio-demographic characteristics and employment conditions. Methods Cross sectional interview-based questionnaire study and measurements (blood pressure, high, weigh) in 196 typist and 134 administrative workers from the same company in Colombia (response 100%). Logistic regression models adjust to type of work, job demand control, Effort-Reward-Ratio, social support, age, gender and overweight. Results The prevalence of hypertension in workers was 17.82%. The age of workers was from 20 to 39 years (76.3%). From the participants with high blood pressure, 31.2% had overweight, 21% reported high tension and 20% indicated active job (p 0.36). The most important associations in the logistic regression, was overweight (OR 4.6; 95% CI: 2.1 to 9.9), age between 30 and 40 years (OR 2.75; 95% CI: 1.1 to 6.5), high social support (OR 2.45; 95% CI: 1.1 to 5.1) and active job (OR 3.36; 95% CI: 1.1 to 10.2). Conclusions This study results indicate an increment of the prevalence of hypertension in Colombian young people, related to the epidemiological transition. It is an evidence of the need to shift the orientation of the country health programs to chronic diseases, such as the hypertension and overweight

Tribological properties of diamond-like-carbon coating doped with tungsten

This paper presents the tribological properties of diamond-like-carbon coatings (DLC) doped with tungsten. The hardness of the DLC coating was determined using a micro-hardness tester. Friction tests were carried out on a tribometer in rotational motion in a 100Cr6 steel ball-disk association with a-C-H:W tungsten doped hydrogenated DLC coating. Tests were carried out with loads of 10 N, 25 N and 50 N under technically dry friction conditions. Using a scanning electron microscopy (SEM), the surface morphology was observed, and with a confocal microscope, the geometric structure of the surface was observed before and after the friction tests. The wetting angle of the samples was examined on an optical tensiometer for distilled water and diiodomethane. The results indicated that DLC coatings of the a-C:H:W type obtained by the PVD technique can be used in unlubricated high-load tribological systems