The desired properties of a mechanical face seal are low friction and low wear rate. To fulfil th... more The desired properties of a mechanical face seal are low friction and low wear rate. To fulfil these requirements the seal material needs a low friction coefficient, high hardness, high corrosion resistance, high thermal conductivity and a high thermal shock resistance. Diamond displays a low friction against almost all materials. Furthermore, diamond shows the highest hardness of all materials, is extremely corrosion resistant, has the highest thermal conductivity (four times that of copper) and has a high thermal shock resistance. Therefore, diamond has the potential of becoming a very competitive seal material. The use of diamond in this kind of application has not yet been realised since it is an expensive material and very difficult to shape into complex geometries. However, it has recently become possible to deposit diamond coatings onto various substrate materials with the desired shape and thereby give the component diamond properties.The objective of this study is to investigate the performance of diamond coated cemented carbide as a face seal material. Laboratory dry sliding tests have been performed as well as component tests with water as the pressure medium. Commercial face seals were used as reference. The results show that diamond coatings considerably lower the friction in mechanical face seals and are therefore an interesting alternative to seal materials commercially available today. The benefits from using diamond coatings include lower running cost, increased reliability and the possibility to use a more simple seal design.
The wetting properties of diamond surfaces have been theoretically and experimentally investigate... more The wetting properties of diamond surfaces have been theoretically and experimentally investigated in the temperature range of 200-700 °C. It was experimentally observed that the conversion from hydrophobic to hydrophilic surfaces will be more efficient with an increase in temperature when using a mixture of H2O and O2 in a wet-oxidation furnace, or only O2 in a dry-oxidation furnace. This
European Journal of Vascular and Endovascular Surgery, 1996
Symptoms of the fistula occurred after a median interval of 90 months which is significantly late... more Symptoms of the fistula occurred after a median interval of 90 months which is significantly later than the previous series (32 months; p < 0.05). The commonest presentation was bleeding followed by septis. The median diagnostic delay was 10.5 days, which was significantly shorter ...
To validate a method for calculating split renal function from computed tomography (CT) compared ... more To validate a method for calculating split renal function from computed tomography (CT) compared with gamma camera renography, and to test a new method for the measurement based on a volume-rendering technique. Thirty-eight patients, aged 65.7 +/- 11.6 (range 37.8-82.1) years, who had undergone both CT angiography and gamma camera renography for a suspected renal artery stenosis were included in this study. Split renal function was calculated from the CT examinations by measuring area and mean attenuation in the image slices of the kidneys, and also by measuring volume and mean attenuation from a 3D reconstruction of the kidneys. Gamma camera renography with 99mTc-MAG3 with or without captopril enhancement was used as a reference. The 2D CT method had good correlation with renography (r=0.93). Mean difference was 4.7 +/- 3.6 (0-12) percentage points per kidney. There was also excellent correlation between the two CT methods (r=1.00). CT is equivalent to renography in determining split renal function, and the measurement from the CT examination can be made more quickly and equally accurately with a 3D technique.
A vascular registry was set up in southern Sweden covering all peripheral vascular procedures per... more A vascular registry was set up in southern Sweden covering all peripheral vascular procedures performed in a population of almost 2 million. During the first year 1569 procedures were registered including 30-day follow-up, making a frequency of 84 per 100,000 inhabitants with a considerable variation between counties, from 42 to 146 procedures per 100,000 inhabitants. The operations were performed by 127 different surgeons, but only nine surgeons performed more than 50 operations each. These surgeons participated in 52.6% of all procedures. The frequency of re-operation differed from 4.0 to 17.9% between hospitals. One month postoperatively 70% of the patients had returned home while 13.2% were still in hospital. Median length of stay was 8 days. Overall mortality was 7.9%. The outcome at 30 days for various procedures was comparable with that of other recent reports from specialised centres.
The desired properties of a mechanical face seal are low friction and low wear rate. To fulfil th... more The desired properties of a mechanical face seal are low friction and low wear rate. To fulfil these requirements the seal material needs a low friction coefficient, high hardness, high corrosion resistance, high thermal conductivity and a high thermal shock resistance. Diamond displays a low friction against almost all materials. Furthermore, diamond shows the highest hardness of all materials, is extremely corrosion resistant, has the highest thermal conductivity (four times that of copper) and has a high thermal shock resistance. Therefore, diamond has the potential of becoming a very competitive seal material. The use of diamond in this kind of application has not yet been realised since it is an expensive material and very difficult to shape into complex geometries. However, it has recently become possible to deposit diamond coatings onto various substrate materials with the desired shape and thereby give the component diamond properties.The objective of this study is to investigate the performance of diamond coated cemented carbide as a face seal material. Laboratory dry sliding tests have been performed as well as component tests with water as the pressure medium. Commercial face seals were used as reference. The results show that diamond coatings considerably lower the friction in mechanical face seals and are therefore an interesting alternative to seal materials commercially available today. The benefits from using diamond coatings include lower running cost, increased reliability and the possibility to use a more simple seal design.
The wetting properties of diamond surfaces have been theoretically and experimentally investigate... more The wetting properties of diamond surfaces have been theoretically and experimentally investigated in the temperature range of 200-700 °C. It was experimentally observed that the conversion from hydrophobic to hydrophilic surfaces will be more efficient with an increase in temperature when using a mixture of H2O and O2 in a wet-oxidation furnace, or only O2 in a dry-oxidation furnace. This
European Journal of Vascular and Endovascular Surgery, 1996
Symptoms of the fistula occurred after a median interval of 90 months which is significantly late... more Symptoms of the fistula occurred after a median interval of 90 months which is significantly later than the previous series (32 months; p < 0.05). The commonest presentation was bleeding followed by septis. The median diagnostic delay was 10.5 days, which was significantly shorter ...
To validate a method for calculating split renal function from computed tomography (CT) compared ... more To validate a method for calculating split renal function from computed tomography (CT) compared with gamma camera renography, and to test a new method for the measurement based on a volume-rendering technique. Thirty-eight patients, aged 65.7 +/- 11.6 (range 37.8-82.1) years, who had undergone both CT angiography and gamma camera renography for a suspected renal artery stenosis were included in this study. Split renal function was calculated from the CT examinations by measuring area and mean attenuation in the image slices of the kidneys, and also by measuring volume and mean attenuation from a 3D reconstruction of the kidneys. Gamma camera renography with 99mTc-MAG3 with or without captopril enhancement was used as a reference. The 2D CT method had good correlation with renography (r=0.93). Mean difference was 4.7 +/- 3.6 (0-12) percentage points per kidney. There was also excellent correlation between the two CT methods (r=1.00). CT is equivalent to renography in determining split renal function, and the measurement from the CT examination can be made more quickly and equally accurately with a 3D technique.
A vascular registry was set up in southern Sweden covering all peripheral vascular procedures per... more A vascular registry was set up in southern Sweden covering all peripheral vascular procedures performed in a population of almost 2 million. During the first year 1569 procedures were registered including 30-day follow-up, making a frequency of 84 per 100,000 inhabitants with a considerable variation between counties, from 42 to 146 procedures per 100,000 inhabitants. The operations were performed by 127 different surgeons, but only nine surgeons performed more than 50 operations each. These surgeons participated in 52.6% of all procedures. The frequency of re-operation differed from 4.0 to 17.9% between hospitals. One month postoperatively 70% of the patients had returned home while 13.2% were still in hospital. Median length of stay was 8 days. Overall mortality was 7.9%. The outcome at 30 days for various procedures was comparable with that of other recent reports from specialised centres.
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Papers by H. Björkman