纳米碳酸钙、稀土粒子用作润滑油添加剂的摩擦学性能和机理研究

【作者】 陈志刚；

【导师】 顾卓明； 顾彩香；

【作者基本信息】 上海海事大学 ， 轮机工程， 2004， 硕士

【摘要】 随着科学技术的发展，对润滑油及其添加剂的要求也在逐年提高，人们已逐渐认识到许多油溶性抗磨减摩添加剂的最终作用形态常常是无机化合物。无机化合物添加剂常常能够较好地提高油品的承载能力和极压性能，但是常规数量级的无机粒子在润滑油中的分散性能差，因此严重制约了它们的应用，纳米技术在润滑油中的应用为解决该问题提供了新思路。本文对纳米碳酸钙、稀土粒子的表征、摩擦学性能以及抗磨、减摩机理进行了研究，得出的主要结论如下： 1、采用D／max-rB型旋转阳极靶多晶X射线衍射仪测定了纳米碳酸钙、稀土粒子的晶体结构和平均粒径大小，同时用透射电子显微镜（TEM）观察其形貌和测定粒径大小，测定结果为：纳米CaCO₃和纳米稀土粒子均呈球状，粒径分别为40nm和11nm左右。 2、根据表面活性剂的亲水亲油平衡值（HLB值）选择了吐温-20、吐温-60、司本-20和聚醚作为纳米碳酸钙和稀土粒子的表面活性剂，试验结果表明这几种表面活性剂以及两种纳米粒子共同产生了很好的协同效应，较好地解决了纳米粒子在润滑油中的分散和稳定问题。 3、通过在磨损试验机上对纳米碳酸钙、稀土粒子润滑油添加剂的摩擦学特性进行的研究，结果表明，这两种粒子作为润滑油添加剂的关键是纳米微粒团簇的分散性和稳定性，只有纳米微粒均匀分散与稳定存在时，才能起到耐磨、减摩作用。 4、纳米碳酸钙和纳米稀土的混合粒子的最佳的添加量为：CaCO₃ Wt％：稀土Wt％=1：1，浓度为0.6％。 5、通过SEM、EDS分析测试和XPS研究，对纳米碳酸钙和纳米稀土的混合粒子的摩擦化学性能进行了研究， 6、探讨了纳米碳酸钙和纳米稀土粒子的复合协同抗磨减摩机理，提出了自己的个人见解： （1）纳米碳酸钙、稀土粒子在摩擦副表面沉积并发生摩擦化学反应，生成化学反应膜，可起到保护摩擦副表面的作用； （2）纳米碳酸钙和稀土的平均粒径分别为40nm和11nm，它们在摩擦副之间起的作用各异，其中碳酸钙可能类似于“微滚珠”起到承载的作用，而稀土粒子由于粒径比较小，可能起到填充修复的作用。 （3）纳米碳酸钙与稀土粒子必须在具有合适的配比的情况下，才能协同起到抗磨、减摩作用。在纳米碳酸钙粒子多，稀土粒子少时，主要是“微滚珠”的承载作用去海海事大李硕士格灰俩来破城妈.稀土牡子用作润淆油添加刑的厚莽李牲倪和机理研究为主;在纳米碳酸钙粒子少，稀土粒子多时，主要是“填充修复”作用为主。上述两种情况都不能充分发挥各自作用以及协同效应。在本研究中纳米碳酸钙与稀土粒子配比为1:1时，形成纳米碳酸钙粒子在被纳米稀土粒子填平修复的表面上起到“微滚珠”的作用，充分发挥了抗磨、减摩协同效应。 （4）纳米碳酸钙、氧化钙、稀土粒子通过摩擦过程中的摩擦化学作用在磨斑表面上形成了新的沉积膜，不仅阻止了摩擦表面之间的直接接触，而且拥有很高的的承载能力，使得由剪切应力引起一的弹性变形和塑性变形局限于润滑膜区域，因而有效地抑制了摩擦表面的粘着磨损和接触疲劳。 （5）少量钙离子和稀土金属离子还原生成的金属单质通过扩散作用渗透到钢基体表面，形成表面强化层，提高了表面的耐磨性，起到了抗磨作用。 本文所做工作是对多种纳米粒子共同作为润滑油添加剂性能研究领域的探索性工作，是上海市科委项目“纳米材料用于润滑油剂添加剂的摩擦机理研究”和上海市教委重点基金项目“纳米材料在润滑技术中的应用”中的一部分，大量的工作还需要在今后继续深入研究。更多还原

【Abstract】 With the development of modern science and technology, requirements to lubricating oil and its additives are increasing year by year, people get to know that the oil-soluble anti-wear and friction-reducing additives’ final functionary conformation are always inorganic compounds. And they always can perfectly increase load-carrying abilities and extreme pressure properties of lubricating oil. The applications of inorganic particles are restricted by their dispersing performance. It is the application of nano-materials in lubrication that provides a new clue. The characterization, tribological performance and mechanism of anti-wear and friction reduction of nano-particles of CaCO3 and rare earths are studied in this paper. The main conclusions are reached as followed.1. The crystal structure and average sizes of nano-particles of CaCO3 and rare earths have been tested by a D/max-rB X-ray diffractometer. And the shapes and average sizes of nano-particles of CaCO3 and rare earths have been measured through TEM. The results indicated that both nano-particles of CaCO3 and rare earths appeared in spherical powder, and their diameters are 40nm and 11 nm, respectively.2. On the basis of HLB values suitable surfactant such as Tween-20, Tween-60, Span-20and Polyether are selected. The results show that they have nano-particles receiving very good dispersiveness and stability in the lubricating oil.3. Tribological performances of nano-particles of CaCO3 and rare earths as lubricating oil additives were studied in friction and wear test machine. The results indicated that dispersion and stability of nano-particles are key factor to use them as lubricating oil additives. Only with evenly-distributed cluster can the function of anti-wear and friction reduction be achieved.4. The optimal proportion of nano-particles of CaCO3 and rare earths is: CaCO3 (Wt%) : rare earths( Wt%)=1 : 1, and the content is 0.6% .5. The tested results of nano-particles of CaCO3 and rare earths’ tribological chemical properties are studied through Scanning Electron Microscope(SEM), Energy Dispersion Spectrum(EDS) and X-ray Photoelectron Spectrum(XPS).6. The mechanism of anti-wear and friction reduction of nano-particles of CaCO3 and rare earths has been discussed and individual opinions of the nano-particles have been proposed.1)Nano-particles of CaCO3 and rare earths deposit on the friction surface, and tribological chemical reaction takes place, producing chemical reactive film, which can keep friction surface from wearing.2) Nano-particles of CaCO3 and rare earths appeared in spherical powder with the diameter of 40nm and 11 nm, respectively. They have different functions on friction surface, CaCO3 nano-particles work similar to "tiny ball bearing", which can support loads; and rare earths nano-particle can fill in and repair worn surfaces.3)Only with appropriate proportion, can nano-particles of CaCOs and rare earths concertedly function as properties of anti-wear and friction reduction. When both nano-particles of CaCO3 and rare earths are added in the lubricating oil, more CaCO3 nano-particles work similar to "tiny ball bearing", which can mostly support loads; on the contrary, more rare earths nano-particles mostly fill in and repair worn surfaces. These two nano-particles can’t take effect solely, or work as concerted effect. In our research, when mass of nano-particles of CaCOs and rare earths are the same, CaCO3 nano-particles work as "tiny ball bearing" on the surface which filled by rare earths nano-particle, and function as properties of anti-wear and friction reduction.4) Through tribological chemical reaction, the nano-particles of CaC03, CaO and rare earths nano-particles form a deposited film on the worn surface, and improve anti-wear property of friction surface. It not only keeps friction surfaces from contacting directly, but also supports loads, so elastic deformation and plastic deformation caused by shearing stress are limited in lubricating films area, result in restraining adhesion wear and contacting fatigue o更多还原