Fabrication and drilling tests of chemical vapor deposition diamond coated drills in machining carbon fiber reinforced plastics

Chemical vapor deposition (CVD) diamond coated drills are fabricated by depositing diamond films on Co-cemented tungsten carbide (WC-Co) drills. The characteristics of as-deposited diamond coatings are investigated by scanning electron microscope (SEM) and Raman spectra. To evaluate the cutting performance of diamond coated drills, comparative drilling tests are conducted using diamond coated and uncoated WC-Co drills, with carbon fiber reinforced plastics (CFRPs) as the workpiece on a high-speed computer numerical control (CNC) machine. Thrust force and tool wear are measured during the drilling process. The results show that diamond coated drill exhibits better cutting performance, compared with the uncoated drill. The value of flank wear is about 70 μm after machining 90 holes, about a half of that of theWC-Co drill with 145μm after drilling only 30 holes. The wear rate of WC-Co drill is higher than that of diamond coated drill before diamond films peeling off. The diamond coated drill achieves more predictable hole quality. The improved cutting performance of the diamond coated drill is due to the high hardness, wear resistance and low coefficient of friction.     

基于PCMS系统结构专业材料预测的应用研究

随着海洋石油工程(青岛)有限公司在生产项目管理精细化方面不断提高,项目管理团队对PCMS系统在结构专业材料预测提出更高的管理需求。本文以原材料供货紧缺的MDS(Multiple Discipline Support)下料和预制阶段为应用场景,阐述通过应用PCMS系统现有功能辅以软件定制开发实现材料精准预测,提供施工决策,优化施工路径,并在企鹅FPSO项目上成功应用。     

Simulation of temperature distribution in hot filament chemical vapor deposition diamond films growth on SiC seals

In this study, the temperature and gas velocity distributions in hot filament chemical vapor deposition(HFCVD) diamond film growth on the end surfaces of seals are simulated by the finite volume method. The influence of filament diameter, filament separation and rotational speed of the substrates is considered. Firstly,the simulation model is established by simplifying operating conditions to simulate the temperature and gas velocity distributions. Thereafter, the deposition parameters are optimized as 0.6 mm filament diameter, 18 mm filament separation and 5 r/min rotational speed to get the uniform temperature distribution. Under the influence of the rotational speed, the difference between temperature gradients along the directions perpendicular to the filament and parallel to the filament becomes narrow, it is consistent with the actual condition, and the maximum temperature difference on the substrates decreases to 7.4?C. Furthermore, the effect of the rotational speed on the gas velocity distribution is studied. Finally, diamond films are deposited on the end surfaces of Si C seals with the optimized deposition parameters. The characterizations by scanning electron microscopy(SEM) and Raman spectroscopy exhibit a layer of homogeneous diamond films with fine-faceted crystals and uniform thickness. The results validate the simulation model.     

湿陷性黄土路基常见病害及防治措施

湿陷性黄土遇水浸湿时， 土的强度显著降低， 对工程造成的危害性很大。 文章通过介绍湿陷性黄土的结构组成及其分类评价， 分析了其产生常见病害及成因， 从设计和施工方面提出了相应的防治措施， 为今后实际工程的设计和施工提供一定的指导和借鉴意义。     

青岛市要求汽修行业明码标价率达到100％

近日,青岛市物价局印发了《2012年市场价格监管工作方案》（下简称《方案》）,方案规定,今年将严查商家不明码标价行为。对一切市场价格违法行为采取“零容忍”。其中．不仅要使辖区客运站、停车场等经营单位按规定的内容和方式明码标价率达到100％。同时要求汽车维修服务单位明码标价率达到100％,解决让车主头疼的汽修乱收费现象。     

Friction and cutting properties of hot-filament chemical vapor deposition micro- and fine-grained diamond coated silicon nitride inserts

The micro-crystalline diamond (MCD) and fine-grained diamond (FGD) films are deposited on commercial silicon nitride inserts by the hot-filament chemical vapor deposition (HFCVD) method. The friction and cutting properties of as-deposited MCD and FGD films coated silicon nitride (Si₃N₄) inserts are comparatively investigated in this study. The scanning electron microscopy (SEM) and Raman spectroscopy are adopted to study the characterization of the deposited diamond films. The friction tests are conducted on a ball-on-plate type reciprocating friction tester in ambient air using Co-cemented tungsten carbide (WC-Co), Si₃N₄ and ball-bearing steel (BBS) balls as the mating materials of the diamond films. For sliding against WC-Co, Si₃N₄ and BBS, the FGD film presents lower friction coefficients than the MCD film. However, after sliding against Si₃N₄, the FGD film is subject to more severe wear than the MCD film. The cutting performance of as-deposited MCD and FGD coated Si₃N₄ inserts is examined in dry turning glass fiber reinforced plastics (GFRP) composite materials, comparing with the uncoated Si₃N₄ insert. The results indicate that the lifetime of Si₃N₄ inserts can be prolonged by depositing the MCD or FGD film on them and the FGD coated insert shows longer cutting lifetime than the MCD coated one.     

液态CO_2输送管道弯管处冲刷腐蚀数值模拟

由于沿程阻力和外界环境的变化,液态CO_2管道内的CO_2会发生相态转变,含有杂质水的液态CO_2夹带的气态CO_2会对管道弯管处产生冲刷腐蚀。为了描述管道内部的冲刷腐蚀规律,利用ANSYS CFX软件对90°弯管的冲蚀现象进行数值模拟。模拟结果表明:冲蚀速率在弯管段60°~80°之间取得最大值;入口处流体速度由4 m/s增加到12 m/s,管壁的冲蚀速率由3.92×10-6kg/(m2·s)增加到3.47×10-5kg/(m2·s);随着弯管曲率半径增加,最大冲蚀速率产生位置发生前移。研究结果可为长距离液态CO_2管道铺设提供参考。     

遮帘式板桩码头结构的土压力计算分析

本文利用ABAQUS有限元分析软件,针对某10万t级散货码头遮帘式板桩结构进行数值建模,对比了数值计算结果和理论结果的差异,论证了数值模型的可靠性,分析了差异产生的原因。对比分析了有遮帘存在和无遮帘存在对前墙陆侧土压力和位移的影响,数值计算结果表明,遮帘的存在可以达到减小结构受力和位移的目的。     

某轨道交通声屏障工程深化设计方案

以宁波市轨道交通2号线二期地面高架段、过渡段及敞开段为例,以声环境现状为标准,结合实际情况提出以声屏障为主的噪声治理方案,并对设计方案的治理效果进行了声学模拟。