煤化工高参数球阀密封面耐磨材料与激光强化工艺研究

发布时间：2018-05-27 11:20

本文选题：煤化工 + 高参数　；参考：《兰州理工大学》2016年硕士论文

【摘要】：高参数耐磨球阀是现代煤化工高压、高温工况条件下重要的零部件,而其密封面要求的高硬度等使用性能直接影响阀门的服役寿命。一直以来,由于硬度与工艺实现存在矛盾,耐磨面硬度越高,工艺实现越困难,为此在以往的工程应用基础上开发一种高硬度材料,采用激光工艺熔覆球面实现耐磨熔覆层硬度达62HRC以上结果。总体可以提高煤化工装置的使用周期,提高装置工作效率,降低成本。本文开发出一种复合粉末材料。以Ni60合金粉末为基础,添加45%WC及其它元素,实现合金的固溶强化、第二相强化、晶界强化,WC颗粒硬质项的结晶原理,适量添加了Si、B和Y2O3等纳米物质作为强化元素。结合相计算原理,对粉末配方进行微调元素含量,运用理论控制有害相的生成。使用激光熔覆工艺进行表面熔覆,并对激光熔覆层组织进行显微分析和力学性能、硬度及结合强度等试验与分析,最终确定了粉末最优成分配方为Ni60+45%WC复合粉末。激光熔覆层组织显微结构分析结果表明:复合粉末经激光熔覆,熔覆金属与基体宏观形貌反映结合状况,界面结合处是良好的冶金结合,结合区无明显气孔、裂纹。多层多道合金的组织主要由胞状晶及硬质项弥散分布。EDS和XRD物相分析得到:金属基体Cr4Ni15W的固溶体和具有硬质特点的WC颗粒弥散分布。熔覆层组织中WC颗粒相的面积分数约43%。大量弥散分布的球状WC颗粒保证了涂层组织具有较高的强硬性。显微硬度测试表明:常温下,Ni60+45%WC复合粉末激光熔覆层多层熔覆后的平均显微硬度为63-64HRC,可以满足煤化工特定工况及带有颗粒介质的装置实现长期使用要求。在熔覆试样的基础上经相关工艺的调整,在60球体球面实现多层大面积熔覆,覆层厚度达1-1.5mm以上,熔覆表面经磨削机工,表面质量经PT合格。球体与阀门组装后进行高压泵验及高温热态试验,证明球体熔覆层完好并实现密封功能。
[Abstract]:High parameter wear-resistant ball valve is an important part in modern coal chemical industry under high pressure and high temperature working conditions. The high hardness and other performance of sealing surface directly affect the service life of valve. Because of the contradiction between hardness and technological realization, the higher the hardness of wear-resistant surface, the more difficult the process is. Therefore, a kind of high-hardness material is developed on the basis of previous engineering applications. The hardness of wear-resistant cladding layer is above 62HRC by laser cladding of spherical surface. As a whole, it can improve the life cycle of coal chemical plant, improve the working efficiency of the unit and reduce the cost. In this paper, a composite powder material is developed. On the basis of Ni60 alloy powder, 45%WC and other elements were added to realize the solution strengthening, the second phase strengthening and the grain boundary strengthening of the crystalline principle of the hard term of WC particles. The proper amount of nano-materials such as SiB and Y2O3 were added as strengthening elements. Combined with the principle of phase calculation, the element content of powder formulation was fine-tuned, and the formation of harmful phase was controlled by theory. The laser cladding process was used for surface cladding, and the microstructure of the laser cladding coating was analyzed by microanalysis, mechanical properties, hardness and bonding strength. Finally, the optimum composition of the powder was determined as Ni60 45%WC composite powder. The results of microstructure analysis of the laser cladding layer show that the microstructure of the composite powder is reflected by the macroscopic morphology of the cladding metal and the matrix after laser cladding. The interface bond is a good metallurgical bond. There is no obvious porosity and crack in the bonding zone. The microstructure of multilayer and multichannel alloy was mainly analyzed by cellular crystal and hard term dispersion distribution. EDS and XRD phase analysis showed that the solid solution of metal matrix Cr4Ni15W and the dispersion distribution of WC particles with hard characteristics were obtained. The area fraction of WC particle phase in the cladding structure is about 43%. A large number of dispersed spherical WC particles ensured the high toughness of the coating structure. The microhardness test shows that the average microhardness of laser cladding of Ni60 45%WC composite powder is 63-64HRC after laser cladding at room temperature, which can meet the requirement of long-term application of the equipment with particle medium and specific conditions of coal chemical industry. On the basis of the cladding specimen, the multi-layer large area cladding is realized on the 60 sphere by adjusting the related technology. The cladding thickness is more than 1-1.5mm, the cladding surface is grinded and machined, and the surface quality is qualified by PT. After assembling the ball and valve, the high pressure pump test and the high temperature hot state test were carried out, which proved that the cladding layer of the ball body was intact and the sealing function was realized.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ53;TQ050

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