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Projects / Programmes source: ARIS

Selective plasma oxidation of FeCrAl alloys for extended-lifetime of glow plugs for diesel engines

Research activity

Code Science Field Subfield
2.09.05  Engineering sciences and technologies  Electronic components and technologies  Vacuum technologies 

Code Science Field
T155  Technological sciences  Coatings and surface treatment 

Code Science Field
2.05  Engineering and Technology  Materials engineering 
Keywords
pasma, glow plugs, surface treatment
Evaluation (rules)
source: COBISS
Researchers (24)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  06073  PhD Milan Bizjak  Materials science and technology  Researcher  2017 - 2020  465 
2.  37467  PhD Tilen Brecelj  Manufacturing technologies and systems  Researcher  2019 - 2020  27 
3.  50986  Alen Bučar    Technical associate  2018 
4.  18635  Tatjana Filipič    Technical associate  2017 - 2020  24 
5.  20288  Alojz Gašperčič  Mechanical design  Researcher  2017 - 2020 
6.  24489  PhD Blaž Karpe  Materials science and technology  Researcher  2017 - 2020  221 
7.  20441  PhD Damjan Klobčar  Mechanical design  Researcher  2017 - 2020  570 
8.  18566  PhD Matjaž Knap  Materials science and technology  Researcher  2017 - 2020  142 
9.  52526  Peter Kolar    Technical associate  2018 - 2020 
10.  11624  PhD Borut Kosec  Materials science and technology  Researcher  2017 - 2020  979 
11.  15703  PhD Janez Kovač  Electronic components and technologies  Head  2017 - 2020  682 
12.  33216  PhD Romana Krištof  Public health (occupational safety)  Researcher  2019 - 2020  49 
13.  38392  Ana Lipušček  Mechanical design  Researcher  2017 
14.  52315  Andraž Logar  Electric devices  Researcher  2018 - 2020 
15.  51401  Monika Manfreda  Chemistry  Researcher  2018 - 2020 
16.  10429  PhD Miran Mozetič  Electronic components and technologies  Researcher  2017 - 2020  1,358 
17.  24381  PhD Aleš Nagode  Materials science and technology  Researcher  2017 - 2020  407 
18.  03066  PhD Vincenc Nemanič  Electronic components and technologies  Researcher  2017 - 2020  245 
19.  28609  PhD Matej Pleterski  Materials science and technology  Researcher  2018  70 
20.  38499  Samo Smolej    Technical associate  2017 - 2020 
21.  02045  PhD Janez Tušek  Mechanical design  Retired researcher  2017 - 2020  1,118 
22.  20048  PhD Alenka Vesel  Electronic components and technologies  Researcher  2017 - 2020  697 
23.  31618  PhD Rok Zaplotnik  Electronic components and technologies  Researcher  2017 - 2020  315 
24.  03366  Marko Žumer  Electronic components and technologies  Technical associate  2017 - 2020  110 
Organisations (4)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,855 
2.  0119  HIDRIA, razvoj in proizvodnja avtomobilskih in industrijskih sistemov, d.o.o. (Slovene)  Spodnja Idrija  5045398000  296 
3.  0782  University of Ljubljana, Faculty of Mechanical Engineering  Ljubljana  1627031  29,554 
4.  1555  University of Ljubljana, Faculty of Natural Sciences and Engeneering  Ljubljana  1627074  19,933 
Abstract
The service life of a glow plug in a diesel engine is limited by the lifetime of its heating resistor which is usually made in the form of a wire from the high-temperature-resistive alloy Fe-Cr-Al and operates at 1200 °C. A protective oxide scale of -Al2O3 is formed on the surface of the wire, which protects it against the diffusion of foreign atoms from and to the surrounding atmosphere. However, mechanical stress, thermal shock, different temperature-expansion coefficients of the oxide scale and the substrate may lead to spallation of the Al2O3 protective scale and to degradation of the resistor and, finally, to the failure of the glow plug. There are a variety of approaches used to avoid such damage to the protective oxide scale, but they do not resolve this problem. Our proposal to avoid failure of the Al-oxide film at high temperature and thereby extend the lifetime of the glow plug is the formation of a nanocomposite and homogeneous Al-oxide protective scale/film on the Fe-Cr-Al alloy by selective low pressure plasma oxidation and by the use of modified Fe-Cr-Al alloys. To the best of our knowledge, such a solution has not been proposed before. An oxide film prepared by plasma oxidation should have much better adhesion. Our group at the Jozef Stefan Institute has many years of experience in this field. We propose a low pressure plasma treatment as a proper combination of a reductive and an oxidative plasma treatment using H2 and O2 gases in a two-stage process to provide the selective and controlled formation of a compact and homogeneous Al2O3 layer on the Fe-Cr-Al alloy. The thickness of such a film can be tuned in the range 20–500 nm. Preliminary trials performed on heating wires that were selectively oxidized using a low-pressure plasma in our laboratories and tested at our industrial partner in this project (Hidria AET) show very promising results. In the project we will study the two-phase plasma treatments investigating the duration of phases, the oxidation rate as a function of the density of ions and the neutral species in the plasma, the degree of dissociation, the type of plasma and the discharge conditions. Life-time measurements of the modified glow plugs will be performed at the industrial partner Hidria AET. The third partner in the project (NTF Uni-Lj) will prepare alloys with an increased concentration of Al and other reactive metals (Ti, Zr) by melt-spinning. In this way the influence of alloying elements on the kinetics of oxidation will be followed. Due to changes in the surface chemistry introduced by the plasma oxidation of the heating wires it will be necessary to adopt the existing joining technology for the oxidized heating element on the tube of the glow plug. This will be performed by the fourth project partner (Faculty of Mechanical Engineering, Uni-Lj). We plan to protect the innovative technology derived from the project with international patents, after which we plan to publish the main results in scientific journals. We expect that the improved performance of the glow plug will extend its lifetime by 10-20 %. In this way the industrial partner will gain an advantage over the competition, increase its market share and added value for this product. New generation of glow plugs will fulfil ecological standards, like EURO VI and EURO VII, which are related to lower emissions of nitrogen oxides (NOx) and solid particles having a positive impact on health and general living conditions. The number of employees at Hidria AET is also expected to increase due to the production process of the new product.
Significance for science
During the project a new knowledge on the use of low-pressure plasma for oxidation of metallic materials, in particular Fe-Cr-Al alloys, will be obtained. We will determine the rate and the growth mechanism of oxide layers, as a function of plasma parameters, such as the density of the reactive particles in the plasma, the plasma regime, power, pressure and type of gas. These relations and their impact have not been determined yet for high-temperature resistant alloys such as Fe-Cr-Al alloy. We expect that by using advanced analytical methods such as ToF-SIMS, high resolution XPS, AES, FEG-SEM/EDS, TEM and XRD we will identify and describe the processes on the atomic scale, such as growth kinetics and morphological features of the Al2O3, Cr2O3 and Fe-oxide layers under various conditions during plasma treatment. We will protect innovative knowledge and technology with 1-2 international patents and then publish scientific results in important journals, specialized in the field of surface treatments, oxidation/corrosion or characterization.
Significance for the country
1- Glow plugs are the main product of the industrial partner Hidria-AET; therefore, their main object is long-term improvements in the plugs’ properties. In the past 10 years the main goal of glow-plug development has been to increase the operational temperature, leading to better fuel combustion and, consequently, lower emissions of harmful gases, the shortest possible time for ignition, a low consumption of electrical power, a thinner diameter of the heating wire, improved resistance for high-temperature operation and against aggressive gases, resistance to mechanical vibrations and, as a final result, an extension of the lifetime of the glow plug. We expect that the improved performance of the glow plug proposed in this project will extend its lifetime by 10-20 %. In this way the industrial partner will gain an advantage over the competition, increase its market share and added value for this product. Hidria AET had 16 % of the world’s market share in 2013, and it plans to increase this to 24 % in 2017 and to 35% in 2020. The goal of Hidria AET is to become the leading producer of glow plugs in the world, which it can only achieve with intense R&D activity, of which the proposed project is a vital component, because it relies on the sophisticated technologies only available at the IJS and the other academic partners. 2- The number of employees at Hidria AET is expected to increase in the R&D sector, as well as in the production process of the new product. 3- The profitability of the industrial partner Hidria AET will increase due to the higher added value of the new product that is going to be developed in the frame of this project. This added value is expected to reach that of Hidria AET’s competitors in this field.
Most important scientific results Interim report, final report
Most important socioeconomically and culturally relevant results Interim report, final report
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