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Steel Disks (steel + disk)
Selected AbstractsVerschleißmechanismen bei moderater und extremer GrenzreibungMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 10-11 2004M. Scherge wear mechanisms; continuous wear measurement; surface analysis Abstract Mit einem Stift-Scheibe-Tribometer wurden für das System Stahlstift/Stahlscheibe Versuche durchgeführt, die drastisch unterschiedliche Verschleißraten zur Folge hatten. Durch Wahl der Normalkraft wurde die Energiedissipation so eingestellt, dass im ersten Versuch Verschleißraten in der Größenordnung von Nanometern pro Stunde erreicht wurden, während im zweiten Versuch Mikrometer pro Stunde erzielt wurden. Die Proben wurden nach dem Experiment hinsichtlich Struktur und chemischer Zusammensetzung analysiert. Im Bereich der kleinen Verschleißraten dominierten plastisches Fließen und mechanische Vermischung während die hohen Verschleißraten mit starker Topographieänderung und Oxidation einher gingen. Wear mechanisms at moderate and extreme friction conditions Using a pin-on-disk tribometer drastically different wear rates were obtained in experiments running a steel pin against a steel disk. By tuning the normal force the energy dissipation was varied resulting in either mild wear in the range of nanometers per hour or severe wear with a wear rate of micrometers per hour. After the tribological tests the samples were analyzed with respect to structure and chemical composition. Whereas small wear rates are accompanied by plastic flow and mechanical intermixing, severe wear results in significant topography changes and oxidation. [source] Adhesive bonding of titanium nitride-plated stainless steel for magnetic attachmentsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2001Yohsuke Taira The purpose of this study was to evaluate adhesive bonding of resin to titanium nitride ion-plated stainless steel in order for magnetic attachments to survive in the oral environment. Two primers, Cesead II Opaque Primer (CPII) and Metal Primer II (MPII), and one bonding agent, Super-Bond C&B (SB), were used. The surfaces of stainless steel disks were ground and then plated with titanium nitride. After the primer and SB resin were applied, a self-curing resin was bonded to the metal surfaces. Shear bond strengths were determined after 24 h of water storage and after 2,000 thermocycles. Titanium nitride ion-plated stainless steel showed bond strength comparable to the non-plated material. After thermocycling, all specimens of the group no primer/no SB were debonded. The bond strengths of groups CPII/no SB, MPII/no SB and no primer/SB were significantly lower bond strengths than groups CPII/SB and MPII/SB. An appropriate combination of primer and bonding agent should be selected when bonding a magnetic attachment to the denture base. [source] Metal Objects Mapping After Small Charge Explosions.JOURNAL OF FORENSIC SCIENCES, Issue 3 2006A Study on AISI 304Cu Steel with Two Different Grain Sizes ABSTRACT: Evidence of exposure of a metal component to a small charge explosion can be detected by observing microstructural modifications; they may be present even if the piece does not show noticeable overall plastic deformations. Particularly, if an austenitic stainless steel (or another metal having a face-centered cubic structure and a low stacking fault energy) is exposed to an explosive shock wave, high-speed deformation induces primarily mechanical twinning, whereas, in nonexplosive events, a lower velocity plastic deformation first induces slip. The occurrence of mechanical twins can be detected even if the surface is damaged or oxidized in successive events. In the present research, optical metallography (OM) and scanning electron microscopy (SEM), and scanning tunneling microscopy (STM) were used to detect microstructural modifications caused on AISI 304Cu steel disks by small-charge explosions. Spherical charges of 54.5 or 109 g TNT equivalent mass were used at explosive-to-target distances from 6.5 to 81.5 cm, achieving peak pressures from 160 to 0.5 MPa. Explosions induced limited or no macro-deformation. Two alloy grain sizes were tested. Surface OM and SEM evidenced partial surface melting, zones with recrystallization phenomena, and intense mechanical twinning, which was also detected by STM and X-ray diffraction. In the samples' interior, only twins were seen, up to some distance from the explosion impinged surface and again, at the shortest charge-to-sample distances, in a thin layer around the reflecting surface. For forensic science locating purposes after explosions, the maximum charge-to-target distance at which the phenomena disappear was singled out for each charge or grain size and related to the critical resolved shear stress for twinning. [source] Cement Selection for Cement-Retained Crown Technique with Dental ImplantsJOURNAL OF PROSTHODONTICS, Issue 2 2008James L. Sheets DDS Abstract Purpose: The purpose of this study was to assess and compare the retentive nature of common dental cements that have been adapted for use in the implant abutment cement-retained crown (CRC) technique with those specifically formulated for this purpose. Materials and Methods: Ten regular diameter implant analogs were embedded in stainless steel disks. Unmodified CRC abutments were attached and torqued to 30 Ncm. Test crowns were waxed and cast with base metal alloy. Castings were fitted, cleaned with aluminum oxide, and steam cleaned prior to application of the cement. The cements used were: (1) Temp Bond, (2) UltraTemp, regular, (3) UltraTemp firm, (4) ImProv with petroleum jelly coating of crown, (5) ImProv without petroleum jelly, (6) Premier Implant with KY Jelly coating of abutment, (7) Premier Implant without KY jelly, (8) TR-2, (9) Fleck's, (10) Ketac Cem Aplicap, and (11) Fuji Plus Capsule. After cementation, assemblies were stored for 24 hours. Each sample was subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 5.0 mm/min. Loads required to remove the crowns were recorded, and mean values for each group determined. A one-way ANOVA and a post hoc least square difference (LSD) test were done for pairwise comparison at a confidence interval of 95%. Results: The mean values (±SD) of loads at failure (n = 10) for various cements were as follows (N): Ultratemp, regular 358.6 (±38.2) (Group A), ImProv without petroleum jelly 172.4 (±59.6) (Group B), Fleck's 171.8 (±62.2) (Group B), Ketac Cem 167.8 (±69.1) (Group B), UltraTemp firm 158.8 (±62.7) (Group BC), Fuji Plus 147.5 (±69.7) (Group BC), Premier without KY jelly 131.6 (±31.8) (Group BC), ImProv using petroleum jelly 130.8 (±42.5) (Group BC), Temp Bond 117.8 (±48.3) (Group C), TR-2 41.2 (±16.6) (Group D), and Premier with KY jelly 31.6 (±24.8) (Group D). Groups with the same letter were not significantly different. Conclusions: Within the limitations of this in vitro study, it is not suggested that any one cement is better than another at retaining cement-retained crowns (CRCs) to implant abutments or that a threshold value must be accomplished to ensure retention. The ranking of cements presented is meant to be a discretionary guide for the clinician in deciding the amount of desired retention between castings and implant abutments. [source] | ||||||||||