Influence of Surface Roughness on the Properties of Nitrided Layer on 42CrMo4 Steel.

A crucial factor of a nitriding process of treated parts is surface roughness. Eight samples of 42CrMo4 steel were used to investigate the parameter represented by Ra. In the study, the innovative combined microhardness profiles were used to present results within the compound zone and diffusion layer. Therefore, two loads were applied in the compound zone, 5 gf, and diffusion layer, 500 gf. Observation with SEM and chemical analysis of the investigated samples showed a correlation between microstructure, nitrogen concentration and microhardness of the compound zone. XRD diffraction was used to identify the phase composition. Moreover, the X-ray photoelectron spectroscopy technique was also applied in the study. No distinct correlations between compound zone morphology and the Ra parameter were observed. The thickness value of the structure was constant and fluctuated around 20 µm in the vast majority of the examined cases. However, analysis of the results revealed a dependence between the Ra parameter and diffusion layer thickness. The values of this parameter varied in the range of 356-394 µm depending on the Ra parameter. A distinct nitrided layer was observed on the polished sample.

[Spinal pain syndromes and constitutional hypermobility]. / Zespoly bólowe kregoslupa a hipermobilnosc konstytucjonalna.

INTRODUCTION: The most common cause of spinal pain syndromes (SPS) is overload of the spine. It damages the function of the spine and the morphology of the spine's tissues. The literature suggests that a generalized insufficiency of connective tissue, which manifests itself as a hypermobility of joints (JHM), might be one of the causes of overload. The authors decided to evaluate, whether a frequency of the prevalence of JHM is greater within the population of patients treated because of spinal pain syndromes, and whether JHM might be a pathogenetical factor in sps. MATERIAL AND METHOD: The material consisted of 8014 case records of patients treated in Rehabilitation Clinic because of dysfunctions and diseases of locomotoric system during 7 years. 7061 of those patients were treated for sps. The control group consisted of 953 patients without SPS, treated because of other reasons. All patients underwent an examination to screen for hypermobility. Four simple maneuvers of the peripheral joints and joints of the spine were performed. If hypermobility of joints was detected during testing, the patient underwent a complete examination of 13 tests using the Sasche criteria modified by Kapandij and was interviewed to screen for accompanying symptoms of hypermobility. RESULTS AND CONCLUSIONS: Hypermobility syndrome is recognized much more often in patients with spinal pain syndromes, than in patients treated because of other diseases (7.9% i 0.7%) and twice more often in females than in males (69.7% i 30.3%). Among young people, under 30 years of age hypermobility occurs in 55% of population with SPS. In the youngest patients HMS may be the cause of overload spinal pain syndromes, and a predisposition factor towards spinal pain syndromes in older patients.