GDI发动机沉积物的FTIR及SEM/EDS分析

FTIR and SEM/EDS Analyses of the Deposits from a Gasoline Direct Injection Engine

在一台汽油直喷(GDI)发动机内分别采集进气阀杆、进气阀、活塞顶部和排气口的沉积物,利用傅里叶变换红外光谱法(FTIR)对沉积物原样、有机溶剂提取剩余物和灰分进行结构分析,利用扫描电子显微镜/X-射线能谱仪(SEM/EDS)对沉积物灰分的元素组成和微观形貌进行分析.结果表明:沉积物的有机成分主要由芳香型化合物、链状HC化合物及氧化物组成;灰分的红外谱图显示沉积物中含有S、P和Si等无机非金属元素,这是润滑油中的元素特性;SEM/EDS分析再次证明了上述元素的存在,沉积物中还发现了Ca、Mn、Zn、Al、Mg、K、Cu和Fe等金属元素以及部分卤素,这些元素通常也存在于润滑油中.润滑油是沉积物形成的主要原因.

Deposit samples were collected from several different places including inlet valve stem, inlet valve, piston crown and the inlet of exhaust manifold in a gasoline direct injection （GDI） engine. These original samples, remainders after extracted with organic solvents and ashes were analyzed by using Fourier transform infrared spectros- copy （FTIR）. The analyses of elemental composition and micromorphology of those ashes were also carried out by using scanning electron microscopy/energy dispersive X-ray spectroscopy （SEM/EDS）. The results show that the or- ganic components in the deposits consist mainly of aromatic compounds, hydrocarbon chains and oxides. Inorganic nonmetallic elements like S, P and Si, which are characteristic of engine oil, were observed in the deposits through FTIR analysis of ashes. The SEM/EDS analysis also gives evidence of the exist of these elements. Moreover, metallic elements like Ca, Mn, Zn, A1, Mg, K, Cu, Fe and halogens can be seen in the deposits, and these elements are always found in lubricating oil. Engine oil is the main cause of the deposits formation.