钢包滑板的损毁原因及改进措施

以鞍钢第三炼钢连轧厂钢包用滑板为研究对象,系统总结了滑板使用过程中的损毁现象,并分析了包括热冲击破坏、热化学侵蚀和操作因素在内的损毁原因。在此基础上,从材质、机构选型,滑板安装、使用、维护等角度提出了钢包滑板长寿化措施。     

钙处理钢用连铸中间包滑板的损毁原因与改进措施

介绍了宝钢连铸中间包铝碳锆滑板在浇铸钙处理钢过程中较易发生的异常情况,主要包括滑程的熔损、滑板问的渗钢以及镶锆环滑板的锆环破碎等.从滑板本身质量和实际操作可能存在的问题等方面分析了导致这些异常损毁的原因,并提出了优化滑板的材质体系及结构改进的措施.     

中间包用长寿命铝锆炭滑板的研制与使用

为了提高钢水和连铸坯的质量 ,2 0 0 1年 ,本钢二炼钢中间包浇钢由原来的手动控制改为计算机自动控制 ,同时要求中间包滑板提高使用寿命以实现中间包的长寿命化。我厂原来生产的普通型铝锆炭中间包滑板已经不能满足使用要求 ,因此 ,开发了长寿命的铝锆炭中间包滑板。1　中间包用铝锆炭滑板的损毁本钢的中间包已经实现了浇铸自动化 ,通过计算机自动控制中滑板铸孔的开启度 ,以确保结晶器中钢水液面高度的波动在 3～ 5mm内。使用过程中 ,中滑板始终处于工作状态。下滑板铸孔设计为滞流型 ,虽有利于钢水流态的控制 ,却加剧了中、下滑板的损毁。…     

铝锆炭滑板的热化学侵蚀机理

分析了宝钢３００ｔ钢包滑板使用后的损毁情况。研究了滑板的氧化,铁、锰的氧化物及钙对滑板的化学侵蚀,提出了铝锆炭滑板的热化学侵蚀机理,并指出了滑板的发展方向。     

可重复使用的滑板

为了提高滑板的可靠性和使用寿命,一般采用价格昂贵的高纯原料生产滑板。但是,用后滑板的损毁仅发生在孔周围的小片区域内。为了减少工业废料,降低耐火材料使用成本,日本研究人员研制了一种可循环使用的ECO滑板。设计的ECO滑板的结构示意图见图1。它包括滑板主体     

金属Al/Si结合Al2O3-C滑板的使用损毁分析

用XRD、SEM、EDS和化学分析法对金属Al/Si结合Al2O3-C滑板用后的残砖进行了分析,用后滑板的结构可分为原砖带和工作带两部分.原砖带的主要变化特征为:从低温到高温Al、Si逐渐原位反应生成碳化物和氮化物,使滑板由金属结合转变为非氧化物结合,提高了滑板的高温强度和抗热震性;工作带的主要变化特征为:非氧化物逐渐被氧化,使高温强度降低.金属Al/Si结合Al2O3-C滑板使用损毁过程为:工作带中的非氧化物首先被氧化,氧化后结构疏松,强度降低,在铸孔处由高温钢水冲刷引起铸孔扩大,在滑动面处因机械摩擦造成滑动面拉毛.     

滑板耐热震性的改善

滑板要求具有耐热震性高、耐蚀性高和高温强度高等特性，为此，对各种材质进行了对比研究。添加金属铝的轻烧滑板出现了烧成材质中所不见的异常龟裂。其损毁原因经调查是由于材质的热膨胀率高和装入钢水时发生了烧结，应力集中于水口孔周围所致。为此，应用低膨胀性原料并增加碳添加量，对该材质嘭胀率的下降和弹性模数减小的情况进行了研究。结果发现，其高温强度高于烧成型材质，经实际使用，损毁得到改善，耐热震性优于烧成品。     

滑板材料的抗热震性评价

介绍了滑板材料的抗热震性方面的一些评价方法,主要有模拟试验观察裂纹、基于断裂力学的测试、有限元分析等方法,并指出在滑板材料的评价手段方面还要进一步完善,如利用有限元模拟技术,特别是细观尺度有限元对滑板使用过程进行模拟。     

金属Al-Si结合Al2O3-C滑板的性能和使用

自主研制开发了节能型低碳金属Al-Si结合Al2O3-C滑板,其工艺特点是低温烧成,产品特性是低碳,与常用的Al2O3-C和Al2O3-ZrO2-C滑板相比,具有较高的热态强度,较好的抗热震性和抗氧化性。经大中型钢包的批量使用表明,其连续使用次数是高温烧成Al2O3-C滑板的两倍,与Al2O3-ZrO2-C滑板相当,用后滑板扩孔均匀,拉毛较少,裂纹微细。经残砖分析,认为金属Al-Si结合Al2O3-C滑板使用时的损毁过程可能是:表面工作层的非氧化物首先被氧化,导致结构疏松,强度降低,在铸孔处由高温钢水冲刷引起铸孔扩大,在滑动面处因机械摩擦造成滑动面拉毛。     

钙处理钢用镁尖晶石炭滑板的损毁机理

对宝钢试用的镁尖晶石炭滑板进行了性能检测,并与铝炭锆、锆炭质滑板一起进行了抗CaO渣侵蚀试验,其抗侵蚀性优于后者。对用后的镁尖晶石炭滑板进行了显微结构分析,探讨了滑板的损毁机理。     

60t精炼钢包滑动水口的开发与应用

介绍了烧成铝炭滑板的生产工艺及其和ＹＨＫ－Ⅱ型滑动机构在６０ｔ精炼钢包上的应用。实践证明,精炼钢包采用铝炭滑板及ＹＨＫ－Ⅱ型滑动机构,能够大幅度降低事故率     

Numerical simulation of wear in a C/C composite multidisk clutch

Friction and wear of engineering components are critical factors influencing the product life. In this study a wear simulation method is presented to investigate the wear behavior of a C/C composite multidisk clutch under simulated operation conditions. A modified Archard’s wear model is implemented into a user subroutine which works in association with an axisymmetric finite element model to predict the progress of wear on friction surfaces. An element removal technique is introduced into the finite element analysis to simulate the material loss during wear. Local wear is computed and integrated over the sliding distance using the Euler integration scheme. The progress of wear and wear rate with time and sliding distance is presented.     

Chemical and Mechanical Mechanisms in Wear of Sapphire on Steel

Further evidence of chemical and mechanical mechanisms contributing to the wear process was obtained. Single-crystal sapphire spheres were worn by a rotating steel plate, unlubricated, at sliding speeds from 1000 to 2000 fpm and loads of 2 and 4 lb. Electron microprobe analysis, Becke line analysis, and electron photomicrographs confirmed the gradual buildup of the FeO.Al₂O₃ spinel on the wear surface. Wear rate anisotropy as a function of sliding direction on a plane 12° to the basal plane correlated with the presence or absence of plastic flow as evidenced by slip bands. Fracture of the sapphire during wear was a function of crystal perfection and sliding direction on the basal plane.     

Dry Sliding Wear Properties of Ultra-high Molecular Weight Polyethylene Parts Made by the Injection Molding Process

The objective of this study was to investigate the effects of various sliding wear test conditions on the tribological properties of UHMWPE. The results indicated that the wear resistance of UHMWPE in the sliding direction perpendicular to the melt flow direction was stronger than that in the sliding direction parallel with the melt flow direction. It was found that the X-Z plane obtains more serious incomplete molecular bondings and cracks than the Y-Z plane. The main wear mechanisms were plastic deformations and wrinkled formations. The UHMWPE hardness increases or decreases as the applied load and sliding frequency increases or decreases.     

Tribological behavior of carbon nanotube and polytetrafluoroethylene filled polyimide composites under different lubricated conditions

The friction and wear behavior of polyimide (PI) composites reinforced with carbon nanotube (CNT) and polytetrafluoroethylene (PTFE) were comparatively evaluated under dry sliding, water‐, oil‐ or alkali‐lubricated condition. The wear mechanisms of the composites were also discussed. Results indicate that, when comparison with the dry friction situation, PI‐based composites results lower friction coefficients and wear rates under oil‐ or alkali‐lubricated condition. The lowest wear rate of the CNT/PTFE/PI composite is recorded as 1.2 × 10⁻⁶ mm³/Nm during the composite sliding in alkali, which is only about 40% of the value sliding under dry friction condition. The worn surface of neat PI under dry sliding is characterized by severe adhesive wear, whereas abrasive wear is the main character for CNT/PTFE/PI composites. The worn surfaces of CNT/PTFE/PI composites sliding in oil or alkali lubricated condition are smoother than those under dry or water condition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Role of internal additives in the friction and wear of carbon‐fiber‐reinforced polyimide

Polyimide composites should function in sliding contacts under high temperatures, but the interference of carbon fibers with sliding mechanisms is difficult to predict: they often increase the coefficients of friction and act abrasively but show lubricating properties under other conditions. The friction and wear behavior of thermoplastic polyimides reinforced with short carbon fibers and filled with solid internal lubricant (polytetrafluoroethylene) or silicon oil was investigated in this study with a reciprocating cylinder‐on‐plate tester under 50 N at 0.3 m/s with steel counterfaces that were heated at 23–260°C. We concluded that polytetrafluoroethylene additives effectively reduced the coefficients of friction over the entire temperature range, especially under thermally controlled sliding conditions at 120°C, whereas the internal silicon oil increased the coefficients of friction. The wear rates of the fiber‐reinforced polyimide significantly decreased with respect to those of the thermoplastic polyimide, whereas additional fillers slightly increased the wear rates. We further analyzed the role of internal additives by considering the deformation and maximum polymer surface temperature during sliding. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Softening and melting mechanisms of polyamides interfering with sliding stability under adhesive conditions

The thermal stability of polymers is a main issue when used as friction elements under dry sliding. Cast polyamide grades processed with either natrium or magnesium catalysors are slid on a small-scale and a large-scale test configuration to reveal the effect of softening or degradation on the sliding stability and to investigate possibilities for extrapolation of friction and wear rates between both testing scales. The combination of softening and afterwards transition into the glassy state is detrimental for the sliding stability of natrium catalysed polyamides, characterised by heavy noise during sliding. A transfer film formed under continuous softening also provides high friction. Melting during initial sliding is necessary for stabilisation in both friction and wear, and eventual softening of a molten film near the end of the test then not deteriorates the sliding stability. Softening of magnesium catalysed polyamides is favourable for the formation of a coherent transfer film resulting in more stable sliding than natrium catalysed polyamides. The differences in softening mechanisms of both polyamide grades is correlated to structural changes investigated by thermal analysis and Raman spectroscopy: the γ crystalline structure prevails in magnesium catalysed samples and the α crystalline structure is predominant in natrium catalysed samples. For internal oil lubricated polyamides, a time dependent degradation of the polyamide bulk deteriorates the supply of internal oil lubricant to the sliding interface, resulting in high friction and wear under overload conditions. As the degradation mechanisms during sliding are strongly correlated to the test set-up, extrapolation is only possible for friction in a limited application range, while wear rates cannot be extrapolated.     

Thermal transitions in polyimide transfer under sliding against steel,investigated by Raman spectroscopy and thermal analysis

Polyimides (PI) are known for their extremely high thermal stability and lack of a glass transition temperature below their decomposition point. Therefore, they are frequently used in high‐demanding tribological applications. The tribological characteristics of sintered polyimide (SP‐1) are presently investigated as a function of the sliding temperature that is artificially varied between 60°C and 260°C under fixed load in counterformal contact with a steel plate. For obtaining low friction and wear, a transfer film needs to develop onto the sliding counterface, induced by viscous polymer flow. As surface plastification is more difficult for high‐performance materials, for example, polyimide, a transition towards low friction and stabilized wear rates is observed at temperatures higher than 180°C in accordance with the occurrence of plate‐like transfer particles, while high friction and no transfer was observed at lower temperatures. This transition is correlated to a peak value in both friction and wear at 180°C and is further explained by Raman spectroscopy performed on the worn polymer surfaces and temperature‐modulated differential scanning calorimetry. It is concluded that the intensity of C‐N‐C related absorption bands is minimal at 180°C and is complementary to the intensity of the C?C phenylene structure that is maximal at 180°C. The orientation of the C‐O‐C structure slightly decreases relative to the sliding surface at higher bulk temperatures. The amount of C?O functional groups is the lowest at 140°C, while its orientation progressively enhances at higher bulk temperatures. At 140°C also, the lowest wear rates were measured. The 180°C transition temperature with a peak value in both friction and wear corresponds to a secondary transition measured in the specific complex heat capacity, pointing out that the overall bulk temperature is presently more important than local flash temperatures for causing transitions in tribological behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1407–1425, 2006     

A novel methodology for evaluating wear behavior of rubber composites under combination of sliding and rolling conditions

The wear behavior of tire tread rubber composites has attracted widespread attention of researcher duo to its serious environmental pollution and high frequency of occurrence for a long time. Herein, a new test method is developed, an improved Akron friction testing machine on a laboratory scale was utilized to estimate the wear loss and mechanism of the rubber composites under rolling and sliding coupling condition. The results indicated that the wear loss quickly increases with the increase of the relative sliding velocity. The main wear mechanism, including adhesive, thermofatigue, tear and curl wear, was governed by the thermal deposition of the worn surface. Scanning electron microscope analysis showed thermal decomposition tear region gradually expanded on the worn surface by increasing relative sliding velocity. The heat distribution numerical analysis supported the experimental results, which confirmed that the heat distribution of the worn surface is entirely consistent with the distribution of the thermal decomposition tear region.     

Tribological behavior of poly(ether ether ketone) composites filled with potassium titanate whiskers sliding in different media

The friction and wear properties of poly (ether ether ketone) (PEEK) composites filled with potassium titanate whiskers (PTWs) under alkali, water, and dry conditions were investigated. The wear mechanisms in different lubrication situations were studied on the basis of examinations of the worn and counterpart surfaces with scanning electron microscopy and optical microscopy. The results showed that PTWs could obviously increase the wear resistance and reduce the friction coefficient of the PEEK composites under dry sliding conditions. Only when the PTW content was greater than 35 wt % did the wear resistance and friction coefficient deteriorate. Sliding in water caused increases in the wear rate and friction coefficient of the PEEK composites, and the PTW‐filled PEEK composites showed the highest friction coefficient and wear rate under this lubrication condition. On the contrary, sliding in an alkaline solution, the PTW‐filled PEEK composites showed the lowest friction coefficient and almost the same level of wear resistance as that found under the dry condition. Furrows and abrasive wear were the main mechanisms for the PTW‐filled PEEK composites sliding in water. The transfer onto the counterpart rings was significantly hindered with sliding under water and alkali conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010