风机叶轮轴盘螺栓防护措施

我公司5000 t/d线生料立磨循环风机,型号为Y6-2×40-14№30.5,风量86.4万m3/h,额定功率为3550 kW,该风机运行多年以后,检修发现叶轮两侧轴盘固定螺栓出现磨损现象,见图1。因磨损较大,设备存在安全隐患,每次需要更换时,拆卸比较困难,需要使用电气焊,易造成叶轮变形。检修后还需要进行动平衡测试,检修工序繁琐,劳动强度较大。为降低两侧螺栓的磨损,于2017年12月自主研发了风机叶轮轴盘C形螺栓防护装置,以降低磨损,延长使用周期,同时降低了检修时人工劳动强度。开机运行以来,磨损较小,取得了较好的防护效果,具有较好的推广价值。     

一种简易的磨头喷水装置应用设计

利用简单的材料,结合现场条件,设计制造了一套简易可行的磨头喷水装置,不但能有效降低磨内水泥的温度,更节约了公司的成本以及后期维护更换零配件的费用.     

Enhanced airborne sound absorption effect in poly(vinylidene fluoride)/(K0.5Na0.5)NbO3-nanofiber composite foams

Introducing electrical conductive function to discharge local piezoelectric effect is found effective for improving airborne sound absorption performance. In this work, instead of conductive fillers, a composite with two piezoelectric materials with opposite piezoelectric responses was explored aiming at enhanced sound absorption effect. Open-cell poly(vinylidene fluoride)/(K_0.5Na_0.5)NbO₃ (PVDF/KNN)-nanofiber composite foams were proposed and investigated for airborne sound absorption purpose. Structural and thermal analyses showed that the KNN nanofibers were well dispersed in the PVDF matrix and enhanced the degree of crystallinity of polar phase of PVDF. Significantly enhanced airborne sound absorption over a broad frequency range was observed in the PVDF/KNN-nanofiber composite foams, with increasing KNN nanofibers. One possible mechanism for the improved sound absorption with the piezoelectric KNN nanofibers with positive piezoelectric coefficient added in the PVDF matrix with negative piezoelectric coefficient is that electrical discharge could be facilitated for energy dissipation with the opposite charges generated through the piezoelectric effects in the two phases with opposite polarity. The experimental results show that the open-cell PVDF/KNN-nanofiber composite foams are promising for broadband airborne sound absorption application, and our analysis shed a light on the strategy in designing piezoelectric composite foam with high sound absorption performance.     

Peracetic acid as a single endodontic irrigant: effects on microhardness,roughness and erosion of root canal dentin

The aim was to assess the effects of 1% peracetic acid (PAA) as a single endodontic irrigant on microhardness, roughness, and erosion of root canal dentin, compared with 2.5% sodium hypochlorite (NaOCl) and with 2.5% NaOCl combined with 17% EDTA. Forty human, single‐rooted tooth hemisections were submitted to Knoop microhardness test, before and after the following irrigation protocols: PAA = 1% PAA; NaOCl = 2.5% NaOCl; NaOCl‐EDTA‐NaOCl = 2.5% NaOCl +17% EDTA +2.5% NaOCl; and SS = saline. Another 40 roots were instrumented, irrigated with the same protocols, and sectioned longitudinally. The roughness analysis was performed on the mesial section using a confocal laser scanning microscope, whereas erosion was analyzed on each third of the distal section, using a scanning electron microscope. The data were analyzed using ANOVA and Tukey post‐tests, and Kruskal‐Wallis and Dunn post‐tests (α = .05). The PAA and NaOCl‐EDTA‐NaOCl groups showed no significant differences (p > .05); both promoted reduction in microhardness and increase in roughness, compared with the NaOCl and SS groups (p < .05). NaOCl‐EDTA‐NaOCl promoted higher erosion in the cervical and middle thirds than the other groups (p < .05); there was no difference among PAA, NaOCl, and SS (p > .05). There was also no difference among the groups regarding the apical third (p > .05). PAA used as a single endodontic irrigant caused reduction in root canal dentin microhardness and increase in roughness in a similar way to NaOCl‐EDTA‐NaOCl; however, PAA caused less erosion than NaOCl‐EDTA‐NaOCl.     

Ionic Liquids as Additives in Water-Based Lubricants: From Surface Adsorption to Tribofilm Formation

Tribology Letters - Thickener plays a significant role on the performance of grease, including rheological property, chemical and thermal stability, colloidal and mechanical stability, and so...     

Influence of Nonfunctional Contact Pads on Printed-Circuit Performance

Russian Engineering Research - The need for nonfunctional contact pads at internal layers of multilayer printed circuit boards (PCB) is still under discussion. Published papers argue on both sides...     

纳米技术浮选技术研究进展

本文简述了微细粒矿物资源开发利用现状、纳米技术概况和纳米捕收剂的应用。介绍了纳米技术在微细粒矿物浮选中应用发展趋势。重点介绍了纳米气泡的基本性质、纳米药剂的合成以及纳米捕收剂应用现状。研究发现纳米气泡在微细粒浮选中可以大幅度提高浮选效率,尽可能减小气泡尺寸有利于细矿粒的浮选。纳米药剂的合成存在诸多困难,乳化合成是主要的纳米粒子的合成方法。应用纳米技术合成新型浮选药剂是未来的发展方向。