Wear Metal Analysis in Used Oils- A potential application area of Atomic Absorption Spectroscopy

发动机构成了行业和农业应用的公路运输车，航空和小规模发电的重要发电源。不同类型发动机运行的效率取决于它们的定期维护和监视组件零件状况。每次拆卸发动机既不是实用的，也不是可取的，并通过常规破坏性或非破坏性手段来分析活塞环，活塞，轴承，发动机套管等组件。使用的油分析提供了可行的解决方案，可定期监视发动机组件的工作条件，并帮助决定纠正措施。

Lubricating oils serve as life-line of engines as they prevent excessive wear and tear of moving parts. However, over extended use wear and tear becomes unavoidable and wear metals find their way into the lubricating oils. Atomic Absorption spectroscopy, Optical Emission Spectroscopy and Inductively Coupled Plasma Spectroscopy are conventionally used in analysis of wear metals in used oils. Each technique has its own merits and demerits. Atomic Absorption Spectroscopy, however, provides a commercially viable option on account of its lower price and simplicity of operation.

Engine components are made from different metals and alloys depending on operational requirements. Over extended periods of use constant wear releases metals such as Cr, Cu, Fe, Al, Mg, Na, Ni, Mo, Pb, Si, Sn, Zn or Ti into the lubricating oil. A periodic monitoring of such metals can be helpful in concluding which components are suffering from more wear and undertaking preventive action before major engine breakdowns occur. The table below gives an indication of possible engine parts that have undergo damage due to excessive wear resulting from findings of analysis.

元素	Possibility of damage to component parts
Cr	Piston rings, Cylinder liners
Cu	Bearings, Valve guides
铁	Ball and Roller bearings, Piston rings, Cylinder liners, Gears or due to rusting
莫	Piston rings
Ti	Casings
Sb	Crankshaft and Camshaft bearings
Cd	Bearings

Key Analysis Considerations

Analysis of wear metals by Atomic Absorption Spectroscopy can provide reliable diagnosis of wear of engine parts provided following precautions are kept in mind during sampling and analysis.

• Sample withdrawn should be representative and homogeneous. It is advisable to take more than one sample- preferably 5 samples and homogenize before analysis.
• 莫re frequent monitoring is needed depending on age and usage of an engine or if the content of any particular element is found to be unusually high.
• Sample should be withdrawn when engine is warm with dipstick end at same representative point
• 维护换油或充值的日志。
• Dissolution of oil samples directly in organic solvents such as xylene or methyl isobutyl ketone should be preferred over other methods involving filtration or ashing
• 标准和样品应相同处理以保持相同的特征，尤其是粘度和流量特性
• Adjustable nebulizer should be used to optimize conditions in the flame

根据建议的程序清洁雾化器和喷雾室是必不可少的，以便可以将原子吸收光谱仪用于涉及水溶液的常规应用。