Deposition temperature influence on the wear behaviour of carbon-based coatings deposited on hardened steel

An evaluation regarding the influence of substrate material characteristics and deposition parameters on the tribological behaviour of carbon-based is presented. Chromium nitride interlayers and carbon-based thin films were deposited on hardened AISI 5115 case hardening steel, by magnetron sputtering. The physical vapour deposition (PVD) deposition was performed at three different temperatures: 180 °C, 200 °C and 250 °C. The chemical composition of the samples was assessed by Rutherford Backscattering Spectroscopy (RBS), the structure by X-ray Diffraction (XRD), and the surface morphology by Atomic Force Microscopy (AFM). The surface chemistry was analysed by X-ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy. The coatings are homogeneous, amorphous, with a smooth surface. The mechanical behaviour has been assessed on a pin-on disk rotational tribometer (wear characteristics), on a micro scratch tester (adhesion to the substrate), by ball-cratering (film thickness); by nanoindentation (hardness and the modulus of elasticity). A strong correlation between the substrate characteristics, but more importantly, of the deposition temperature, on one hand, and the mechanical characteristics, on the other hand, has been observed. The fracture toughness is positively influenced by the presence of the ceramic interlayer (chromium nitride). The modulus of elasticity and friction coefficient (both in dry conditions and lubricated) are decreased for higher deposition temperatures, however the higher deposition temperature negatively affects the hardness of the steel substrate.We hereby acknowledge the structural funds project PRO-DD (POSCCE, O.2.2.1., ID 123, SMIS 2637, ctr. no 11/2009) for providing some of the infrastructure used in this work

Low-mass e+e- pair production in 158 A GeV Pb-Au collisions at the CERN SPS, its dependence on multiplicity and transverse momentum

We report a measurement of low-mass electron pairs observed in 158 GeV/nucleon Pb-Au collisions. The pair yield integrated over the range of invariant masses 0.2 < m < 2.0 GeV is enhanced by a factor of 3.5 +/- 0.4 (stat) +/- 0.9 (syst) over the expectation from neutral meson decays. As observed previously in S-Au collisions, the enhancement is most pronounced in the invariant-mass region 300-700 MeV. For Pb-Au we find evidence for a strong increase of the enhancement with centrality. In addition, we show that the enhancement covers a wide range in transverse momentum, but is largest at the lowest observed pt.Comment: 17 pages, 4 figures, submitted to Phys.Lett.

Semi-Hard Scattering Unraveled from Collective Dynamics by Two-Pion Azimuthal Correlations in 158 A GeV/c Pb + Au Collisions

Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-$p_T$ pions ($p_T>$ 1 GeV/$c$) have been measured close to mid-rapidity in 158A GeV/$c$ Pb+Au collisions by the CERES experiment. Elliptic flow ($v_2$) rises linearly with $p_T$ to a value of about 10% at 2 GeV/$c$. Beyond $p_T\approx$ 1.5 GeV/$c$, the slope decreases considerably, possibly indicating a saturation of $v_2$ at high $p_T$. Two-pion azimuthal anisotropies for $p_T>$ 1.2 GeV/$c$ exceed the elliptic flow values by about 60% in mid-central collisions. These non-flow contributions are attributed to near-side and back-to-back jet-like correlations, the latter exhibiting centrality dependent broadening.Comment: Submitted to Phys. Rev. Letters, 4 pages, 5 figure

Diagnosis of IgG4 - related ophthalmic disease in a group of patients with various lesions of the eye and orbits

Purpose of the study. To provide demographic, clinical, laboratory, ultrasound, radiological, morphological/ immunomorphological phenotype of IgG4-related ophthalmic diseases, which allowsmaking a differential diagnosis with granulomatous, autoimmune, inflammatory, endocrine and hematologic diseases affecting the eye and orbits. Materials and methods. From 2004 to 2016 108 (78.2%) of the 138 patients were diagnosed with non-tumoral lesions of eye and orbits. In 48 patients (35%) at admission and 5 patients in the follow were diagnosed IgG4-related ophthalmic disease. In the analysis of 82 (f-44, m-38) patients with IgG4-related disease, localization of lesions in orbit observed in 53 (f-36, m-17) and it was the most frequent involvement in patients with IgG4-related disease (64.5%). Only 7 patients had isolated IgG4-related ophthalmic disease, whereas 46 patients (87%) had involvement of 2-7 locations, as a manifestation of IgG4-related systemic disease.During the examination, the average age of patients with IgG4-related ophthalmic disease was 47.5 years (19-73 years). Median time to diagnosis was 52.8 months before 2004 and 36 months 2004-2016. Results. We noted the predominance of females in the ratio 2: 1 inthe group of patients with IgG4-related ophthalmic disease. Edema of the eyelids, nasal congestion (55-60%), tumor-like formations of the upper eyelids and increased lacrimation prevailed at the onset of the disease, whereas such functional impairment like limited mobility and pain in eyeballs, exophthalmos, ptosis and diplopia appeared later at 15-38% with a loss visual acuity in one case. Bilateral lesion (86%), mainly affecting the lacrimal glands (93.5%), infiltration of the extraocular muscles (83.5%) and retrobulbar tissue with a thickening of the optic nerve in one third of patients were the main localizations IgG4-related ophthalmic disease. Clinical symptoms were accompanied by the appearance of moderate inflammatory activity (38%), increased levels IgG (44%), IgG4(88%) and IgE (61%). Indicators of autoimmune disorders observed in 6-22% of patients, most often in patients with simultaneous involvement of the salivary glands. Significant lymphoplasmacytic infiltration (94%) with a ratio of plasma cells (IgG4/IgG) secreting IgG4> 40% (90%) with fibrosis formation (94%) and follicle formation (71%) with a moderate amount of eosinophils (34%) were the major morphological / immunomorphological manifestations of IgG4-related ophthalmic disease. Signs of vasculitis and obliterative phlebitis were found in a small amount of patients. Conclusion. Determination of elevated levels of IgG-4 / IgE in patients with edema, pseudotumor of the eyelid, sinusitis and increase of the palpebral lobe of the lacrimal gland suggests the presence of IgG4-related ophthalmic disease. Minimally invasive incisional biopsy of lacrimal glands and salivary glands followed by morphological / immunomorphological research is needed for the correct diagnosis. Diagnostic orbitotomy in ophthalmic hospitals in such cases is inexpedient, since it leads to the development of dry eye. Massive lymphoplasmacytic infiltration with IgG4 / IgG ratio more than 40%, advanced fibrosis in biopsiesof the orbits tissue or salivary glands when combined lesions are required for the making the diagnosis of IgG4-related ophthalmic disease

e+e--pair production in Pb-Au collisions at 158 GeV per nucleon

We present the combined results on electron-pair production in 158 GeV/n {Pb-Au} ($\sqrt{s}$= 17.2 GeV) collisions taken at the CERN SPS in 1995 and 1996, and give a detailed account of the data analysis. The enhancement over the reference of neutral meson decays amounts to a factor of 2.31$\pm0.19 (stat.)\pm0.55 (syst.)\pm0.69 (decays)$ for semi-central collisions (28% $\sigma/\sigma_{geo}$) when yields are integrated over $m>$ 200 MeV/$c^2$ in invariant mass. The measured yield, its stronger-than-linear scaling with $N_{ch}$, and the dominance of low pair $p_t$ strongly suggest an interpretation as {\it thermal radiation} from pion annihilation in the hadronic fireball. The shape of the excess centring at $m\approx$ 500 MeV/$c^2$, however, cannot be described without strong medium modifications of the $\rho$ meson. The results are put into perspective by comparison to predictions from Brown-Rho scaling governed by chiral symmetry restoration, and from the spectral-function many-body treatment in which the approach to the phase boundary is less explicit.Comment: 39 pages, 40 figures, to appear in Eur.Phys.J.C. (2005

Recent results from Pb-Au collisions at 158 GeV/c per nucleon obtained with the CERES spectrometer

During the 1996 lead run time, CERES has accumulated 42 million events, corresponding to a factor of 5 more statistics than in 1995 and 2.5 million events of a special photon-run. We report on the results of the low-mass e$^+$e$^-$-pair analysis. Since the most critical item is the poor signal-to-background ratio we also discuss the understanding of this background, in absolute terms, with the help of a detailed Monte Carlo simulation. We show preliminary results of the photon analysis and summarize the results of the hadron analysis preliminarily reported on already at QM'97Comment: 10 pages, 9 figures, Proceedings of the XIV Int. Conf. on Nucleus-Nucleus Collisions,Quark Matter 99, Torino, Italy, May 10 - 15, 199

A doublet of 3" cylindrical silicon drift detectors in the CERES/NA45 experiment

We report on the performance of a doublet of 3" cylindrical silicon drift detectors installed as an upgrade of the CERES/NA45 electron pair spectrometer for the Pb-beam at the CERN SPS. The silicon detectors provide external particle tracking and background rejection of conversions and close Dalitz pairs. Results on vertex reconstruction and rejection from Pb test-run in 1994 are presented