Nickel-titanium versus stainless-steel finger spreaders in curved canals

Fibro-osseous lesions of the sinonasal region are relatively frequent, but those strictly confined to the nasal cavity are rare. We report an atypical fibro-osseous lesion in the nasal cavity and describe its radiological features. The differential diagnosis is discussed.     

Control over the particle size of stainless-steel powders

Conclusions Replacing some of the metallic iron by ferric oxide, Fe₂O₃, in the charge for the preparation of Kh18N15 and Kh23N28 stainless-steel powders by the calcium-hydride reduction process increases (two- to threefold) the yield of the fine fraction (-0.063 mm) without affecting the apparent density of the powders (1.4–1.85 g/cm³) or the sponge shape of their particles. At the present time, stainless-steel powders are being manufactured using a charge in which 20–30% of metallic iron has been replaced by the oxide Fe₂O₃.Translated from Poroshkovaya Metallurgiya, No. 2 (134), pp. 1–8, February, 1974.     

Physicomechanical properties of detonation coatings made from stainless-steel powders

A method has been developed for determining the strength and plasticity characteristics of detonation coatings; the structure and phase factors have been used along with the physicomechanical characteristics and the adhesion to optimize the production conditions. Phase transformations occur during the formation of the coatings that govern the strength, ductility, and tribotechnical properties. In spite of the structural and phase changes that accompany coating formation, layers up to 0.25 mm thick have the properties of the compact materials.Institute of Problems of Materials Science, National Academy of Sciences of the Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 59–66, July–August, 1994.     

Effects of silica addition on chromium distribution in stainless-steel slag

The present study was aimed at highlighting the effect of silica on chromium distribution and enrichment in certain stainless-steel slag when basicity ranged from 0.96 to 1.96. Industrial slag samples of the CaO–Al₂O₃–MgO–SiO₂–CrO_X–Fe_XO system were investigated with different silica addition contents and soaked at the targeted regime. X-ray diffraction, electron probe micro-analyzer with wavelength-dispersive X-ray spectrometer, as well as Fourier-transform infrared spectroscopy and NIH ImageJ software were used for sample characterisation. FactSage version 6.4 was employed to calculate phase equilibria at 1200°C for the slag system to understand the crystallisation procedure. Results indicated that chromium was enriched in CaCr₂O₄ at high basicity, but in spinel at lower basicity. The spinel phase increased in size and chromium distribution with Fe(II) participated in growth with the decrease in depolymerisation of the slag structure.     

Microstructural assessment of nitrogen-strengthened austenitic stainless-steel welds using thermoelectric power

The electronic properties of an alloy correlate directly to its microstructure. The thermoelectric power coefficient has been determined in this investigation to be a rapid and accurate measurement that can be used for microstructural assessment and correlated to achieve the maximum material performance of structural alloys. In high-nitrogen-strengthened stainless-steel welds, nitrogen partitions into solidsolution nitrogen and nitrides during the welding thermal cycle. The formation of nitrides results in a degradation of the mechanical properties and the corrosion resistance. Thermoelectric power measurements offer a means of assessing the weld-interstitial nitrogen content, which allows for a better correlation between the nitrogen content and the weld-metal microstructure and properties. Using pressure-composition-temperature (PCT) (activity) diagrams, thermodynamic models are developed to describe the relationship between the thermoelectric power coefficient as a function of the interstitial nitrogen content and the formed nitride content. These correlations between the electronic property measurements and the interstitial nitrogen content will allow for a faster, nondestructive, and improved property prediction of nitrogen-strengthened stainless steels.     

Performance from using stainless-steel and melybdenum materials for gas-thermal deposition

It is found that one can replace spraying powders by wire in the deposition of gas-thermal coatings, which increases the material use coefficient and reduces the cost. On the whole, the material, labor, and energy costs are reduced by 75.8% (stainless steel) or 35.5% (molybdenum) when powder is replaced by wire, with the economy constituting correspondingly 10.3 and 22.1 rubles per m².Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, No. 1 (361), pp. 95–97, January, 1993.     

Color change and fracture resistance of two preveneered stainless-steel crowns after sterilization

A negative image of community care prevails. This method of care is perceived to be a relatively novel phenomenon and has received mixed media coverage. The negative image of community care has led to the growing belief that this care method has failed. This failure has largely been ascribed to the lack of powers available to control patients in the community and to the method's relative novelty. However, this paper contends that there are two flaws to the above assertion: first, community care is far from new, and second, the inherent problem is not the lack of powers available to control patients in the community, but, essentially, the absence of a secure and stable environment within the community.     

Effect of cooling regime on phase transformation and chromium enrichment in stainless-steel slag

Cooling regime of stainless-steel slag has a great influence on the migration rule of chromium. Effect of cooling rate on chromium distribution in CaO–SiO₂–MgO–Al₂O₃–Fe_xO–Cr₂O₃ system has been studied by FactSage, XRD and SEM-EDS in this paper. Results showed that the main phases in stainless-steel slag are spinel, bredigite, wustite, lime and periclase. Chromium was enriched in the stable phases. With the decrease in cooling rate, the size of chromium-rich phase increased relatively while chromium content in spinel phase reduced. Rapid cooling was favourable to the chromium enrichment in spinel phase in high basicity (high than 2.0) stainless-steel slag.     

连续摩擦焊接虚焊的改进方法

介绍了连续摩擦焊接的工作原理,分析了连续摩擦焊接虚焊产生的原因,并针对性地提出了改进措施。连续摩擦焊接分为预启动、一次摩擦、二次摩擦、顶锻四个阶段,其特点是焊接过程中需要控制三个变量:焊接压力、主轴转速、缩短量。缩短量是衡量焊接是否结束的关键控制要素,同时辅助监控焊接时间。这种控制方法对电气传感器、控制过程要求高,工艺的复杂性大。以Thompson连续摩擦焊机为例,阐述了软硬件结构和控制原理。