Abstract The paper deals with problems related to application of aluminum-silicon alloys for combustion engine cylinder liners

A Trytek

A W Orłowicz

M Mróz

M Tupaj

CiteSeerX

 
A R C H I V E S  
o f  
F O U N D R Y  E N G I N E E R I N G  
 
 
 
Published quarterly as the organ of the Foundry Commission of the Polish Academy of Sciences 
ISSN (1897-3310) 
Volume 15 
Issue 2/2015 
 
71 – 74 
 
15/2 
 
A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 5 ,  I s s u e  2 / 2 0 1 5 ,  7 1 - 7 4  71 
 
Combustion Engine Cylinder Liners  
Made of Al-Si Alloys 
 
A.W. Orłowicz *, M. Tupaj, M. Mróz, A. Trytek 
Department of Casting and Welding, Rzeszow University of Technology,  
al. Powstańców Warszawy 12, 35-959 Rzeszów, Poland 
*Corresponding author. E-mail address: aworlow@prz.edu.pl 
 
Received 23.02.2015; accepted in revised form 31.03.2015 
 
 
Abstract 
 
The paper deals with problems related to application of aluminum-silicon alloys for combustion engine cylinder liners. 
 
Keywords: Combustion engine cylinder liners, Al-Si alloys 
 
 
 
1. Introduction 
 
The reason for which a fast growth of applications involving 
aluminum-silicon alloys can be observed in the automotive 
industry over recent years include the high value of ratio of the 
tensile strength to the mass density, good corrosion resistance, 
good technological properties, and low manufacturing and 
processing costs characterizing these materials. 
Nowadays, in view of more restrictive requirements 
concerning emissions of exhaust fumes, car engine manufacturers 
use prefer castings of light metal alloys in order to reduce engine 
mass which in turn allows to reduce fuel consumption. In view of 
the above, aluminum-silicon alloys have been relatively early 
used to fabricate engine cylinder heads, cylinder blocks, oil 
sumps, and brackets. For a long period of time, a serious problem 
related to manufacturing of cylinder liners of aluminum-silicon 
alloys consisted in making them resistant to abrasive wear and 
seizing.  
In recent years, a number of scientific centers have continued 
their work on the possibility to use that alloy for fabrication of 
combustion engine cylinder liners cylinder in view of its good 
sliding properties and high resistance to abrasive wear. 
Rare results of studies presented in the latest international 
literature [1–3] indicate that scientific and research studies on the 
wear properties of engine cylinder liners made of aluminum-
silicon alloys are currently continued (e.g. at GM Powertrain, 
General Motors Co, in Pontiac and Wixom, as well as at GM 
R&D Center, and General Motors Co in Warren). 
 
 
2. The state of art 
 
Aluminum-silicon alloys used as a material for combustion 
engine cylinder liners are attractive in view of some of their 
specific properties, namely: 
– good thermal conductivity; 
– value of the coefficient of thermal expansion close to this 
characterizing the piston; 
– good behavior in technological processes (casting and 
machining); 
– good immediate and fatigue strength; 
– corrosion resistance in the atmosphere of fuel combustion 
products; 
– possibility to shape cylinder bearing surface geometrical 
properties facilitating retention of lubricant; 
– sufficient resistance to abrasive wear. 
 
72  A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 5 ,  I s s u e  2 / 2 0 1 5 ,  7 1 - 7 4  
Another important merit of Al-Si alloys is their relatively low 
specific weight which allows to reduce the overall mass of the 
engine. Thermal conductivity of these alloys is about three times 
higher than this of cast iron which offers the possibility to reduce 
temperature of the cylinder liner working surface at the same 
engine power output. An engine block made of such alloy gives 
up the heat faster and more evenly, therefore less coolant is 
needed in the cooling system. Thanks to similar value of the 
coefficient of linear thermal expansion characterizing both the 
cylinder liner and the piston, it is possible to maintain high 
stability of the piston play, regardless on the engine operating 
conditions. In view of low casting temperature, thermal load on 
the mould is relatively low in case of aluminum-silicon alloys. 
For this reason, it is possible to fabricate castings with a higher 
dimensional accuracy and better surface quality which in turn 
makes the machining costs lower. Aluminum alloy castings can 
be manufactured in permanent metal moulds which translates 
directly into lower manufacturing costs. Aluminum-silicon alloys 
are consider well-machinable materials, even if their machining 
properties deteriorate with increasing silicon content. 
By performing such operations as modification of liquid metal 
and selection of appropriate cooling rates, it is possible to increase 
significantly both immediate and fatigue strength of Al-Si alloys 
and improve their resistance to abrasive wear. On the other hand, 
thermal treatment aimed at improvement of resistance to abrasive 
wear is not always appropriate, especially in case of castings 
manufactured with the use of conventional pressure casting 
method which can result in dimensional instability caused by gas 
porosity. Aluminum-silicon alloys demonstrate satisfactory 
corrosion resistance in the atmosphere of fuel combustion 
products.  
Studies on application of aluminum-silicon alloys are carried 
out mainly by industrial laboratories and therefore results of such 
studies are rarely published in commonly available technical 
literature, hence the lack of sufficiently in-depth knowledge 
concerning the most favorable microstructure of castings for 
cylinder liners and geometrical parameters of the cylinder bearing 
surface profile securing sufficient retention of lubricant.  
Maintaining adequate thickness of the lubricant layer is of 
critical importance at the stage of engine starting. Available 
knowledge on this subject is limited to cylinder liners made of 
cast iron. It is a well-known fact [4] that if the metallic contact 
between the piston ring and the liner does not occur for 99.9% of 
the engine running time, then the wear is insignificant. If, 
however, the metallic contact exists for 1% of the engine running 
cycle, then the wear becomes high. For contact times longer than 
that, piston rings can break resulting in piston seizure.  
To improve lubrication of the cylinder bearing surface, an 
operation known as honing is performed which consists in 
providing the surface with grooves in which engine oil is retained. 
According to [5], in case of providing a cylinder with grooves of 
constant depth and width, piston rings squeeze the oil out along 
the grooves (Fig. 1). This can result in excessive reduction of 
lubricating layer on the cylinder load bearing surface. As a result 
of local contact occurring between an irregularity on the liner 
surface and the piston ring surface, abrasive wear will increase 
which can result in piston seizing. If appropriate hollows are 
made in the cylinder liner surface, such depressions, once filled 
with engine oil, constitute micro-areas of hydrodynamic 
lubrication. As a result, both friction and the associated wear 
decrease (Fig. 1). This is the reason for which many research 
projects are undertaken on such shaping of cylinder liner surface. 
In case of cast iron liners, laser micro-machining method can be 
used for this purpose [6], while etching is preferred in case of Al-
Si alloys. 
 
 
Fig. 1. Schematic diagram showing interaction between grooves 
and cavities filled with a lubricant on the piston ring/cylinder  
liner surface contact 
 
The first attempts to fabricate cylinder liners from aluminum-
silicon alloys were carried out towards the end of the 1970s. As it 
follows from technical literature of the subject, the monoblock of 
Vega 2300 engine, monoblocks for such cars as Porsche 911, 
Porsche 928, as well as those for certain models of Jaguar, BMW, 
Mercedes, and Audi cars were or currently are manufactured from 
AlSi17Cu4Mg alloy according to a technological process patented 
under the trade name ALUSIL® [7, 8]. Scarlet [9] reports that 
cylinder liners in the BMW Boxter engine, in a block made of a 
magnesium alloy, were made of an aluminum-silicon alloy 
containing 20% silicon and reinforced with Al2O3 fibers. The 
technological process used for fabrication of such liners has been 
patented under the trade name LOKASIL 1®. From other 
published studies it follows that cylinder liners are manufactured 
also of Al-Si alloy containing 27% silicon reinforced with Al2O3 
fibers. The technological process for fabrication of such cylinder 
liners has been patented under the trade mark LOKASIL 2® [10]. 
Available technical literature of the subject reveals 
information about chemistry of aluminum-silicon alloys used 
specifically for cylinder liners (Table 1) together with data 
concerning their microstructure and service properties.  
 
 
 
 
 
 
 
 
A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 5 ,  I s s u e  2 / 2 0 1 5 ,  7 1 - 7 4  73 
Table 1. 
Chemistry of aluminum-silicon alloys used for engine cylinder liners (in % mas.) 
Si Fe Cu Mn Mg Ni Zn Ti Cr Al Source 
11.8–12.7 0.15 1.15–1.45 0.09 1.2–1.5 0.85–1.15 0.04 0.09 – balance [1] 
16–18 0.5 4–5 0.1 0.45–0.65 – 0.1 – – balance [2] 
17 5.0 3.5 – 1,1 – – – – balance [3] 
11.5 0.9 1.15 0.1 1.1 2.5 0.01 0.2 – balance [4] 
17–19 0.7 0.8–1.5 0.2 0.8–1.3 1.3 0.2 0.2 – balance [11] 
16–18 0.5 4–5 0.1 0.4–0.6 – 0.1 – – balance [11] 
22 0.4 1.6 0.3 1.6 0.7 – – – balance [11] 
In the ALUSIL® process, AlSi17Cu4Mg alloy is used, whereas LOKASIL® technology utilizes an aluminum-silicon alloy containing 
20% Si (LOKASIL 1®) of 27% Si (LOKASIL 2®) [12]. 
 
 
It is known from the literature of the subject [13] that low 
content of Mn and Cr favors development of needle-shaped 
phases. Such iron-containing needle-shaped intermetallic phase 
itself in reduction of thermal conductivity. However, an addition 
of Mn (Fe/Mn ratio = 0.5) changes its habit from needle-shaped to 
this resembling Chinese writing, mitigating the negative impact 
on the heat conductivity. Higher chromium contents are favorable 
to occurrence of phase precipitations in the form of polygons. An 
addition of Fe and Ni allows to reduce Cu content without 
affecting the tensile strength. Fe increases hardness, and 
moreover, alloys with low iron content are more expensive. 
Additions of Mg and Cu are practiced in order to increase tensile 
strength and creep resistance. An addition of about 0.5% Ni also 
has a positive effect on creep resistance. Moreover, it must be 
borne in mind that currently, monoblocks are cast with the use of 
the pressure casting method. Typical alloys such as 226, 230, or 
231 contain usually about 1% Fe. US founders use alloys 
containing even up to 2% Fe, in view of the need to reduce 
susceptibility of castings to sticking to the mould.  
On the other hand, there is very little information concerning 
microstructure of the used materials as well as geometrical 
parameters characterizing profile of bearing surface samples. It 
seems that using alloys with hypoeutectic or eutectic composition 
as a material for cylinder liners can turn out to be purposeful in 
case of special techniques of coating bearing surface with a layer 
of material resistant to abrasive wear, e.g. chromium or iron, or in 
case of applying cast-in sleeves. In view of specific conditions 
prevailing in the course of filling a pressure mould with liquid 
metal in conventional pressure machines and high solidification 
rates, the most compact structure of the casting is obtained in its 
regions close to its surface. In areas situated deeper, some 
porosity may develop which reduces resistance to abrasive wear. 
Higher compactness of the casting material can be obtained when 
low-pressure casting methods or pressure methods with negative 
pressure in the mould cavity are used, such as e.g. the 
VACURAL® method. 
Surfaces of castings which are required to show elevated 
resistance to abrasive wear must be provided with cast-in sleeves 
made of alloys characterized with high resistance to abrasive 
wear. In case of engine blocks made of aluminum-silicon alloy, it 
seems to be purposeful to perform cast-in components of 
hypereutectic silumin, with microstructure and surface 
geometrical structure guaranteeing satisfactory resistance to 
abrasive wear and seizing. The required geometrical structure of 
the cylinder bearing surface must be in this case shaped as a cast-
in element by means of etching methods. An example of casting 
provided with a cast-in component is shown in Fig. 2. 
 
 
Fig. 2. An example casting with a cast-in component  
 
 
3. Conclusions 
 
It follows from the state of art in the area of selecting 
chemistries for aluminum-silicon alloys used for combustion 
engine cylinder liners that it is reasonably practicable to provide 
them with cast-in elements of alloys containing even as much as 
about 30% silicon, as in the patent-protected LOKASIL 2® 
technology. It is a fact well-known from the machining practice 
that when large silicone precipitations are present in a aluminum-
silicon alloy, they will be probably torn out from the material in 
the machining stage. 
The process of large silicone precipitations cracking and 
tearing out will be also the cause of excessive abrasive wear and 
seizing of the sliding node. Developing a microstructure of 
hypereutectic alloys optimal from the point of view of eliminating 
the phenomenon of seizing, is the subject of interest in numerous 
scientific centers [14]. Fine silicone precipitations, more favorable 
as far as avoidance of seizing is concerned, can be obtained by 
means of modification of the liquid metal as well as by 
accelerated cooling in the alloy solidification phase. It may prove 
to be a particularly interesting solution to use for this purpose 
such unconventional technique as remelting the casting surface by 
means of concentrated stream of heat from a laser beam [15] or 
electric arc plasma [16, 17]. One may expect interesting effects 
from plasma spraying applied to obtain a gradient coating of e.g. 
74  A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 5 ,  I s s u e  2 / 2 0 1 5 ,  7 1 - 7 4  
NiAl + Al2O3 or applying a plasma-sprayed coat using a powder 
prepared from a Al-Si alloy, containing e.g. 30% Si. 
 
 
References 
 
[1] Hielscher, U. (1989). Aluminiumguss im Kraftfahrzeugebau, 
Aluminium. 65(9), 8-9. 
[2] Ott, R.D., Blue, C.A., Santella, M.L. & Blau, P.J. (2001). 
The influence of a heat treatment on the tribological 
performance of a high wear resistant high Si Al-Si alloy weld 
overlay. Wear. 251, 868-874. 
[3] Timmermans, G. & Froyen, L. (1999). Fretting wear 
behaviour of hypereutectic P/M Al-Si in oil environment. 
Wear. 230, 105-117. 
[4] Kozaczewski, W. (2004). Design of piston-cylinder group. 
Warszawa: Wyd. Komunikacji i Łączności. (in Polish) 
[5] Motormechanik. Volkswagen technical information. 
[6] Burakowski, T., Napadłek, W. & Przetakiewicz, W. (2010). 
Laser micro-machining in modification of superficial layer of 
combustion engine components — selected technological 
applications. Inżynieria Materiałowa. 31(4), 898-904. (in 
Polish) 
[7] Yamagata, H. (2005). The science and technology of 
materials in automotive engines. Cambridge, England: 
Woodhead Publishing Limited and CRC Press LLC. 
[8] Köhler, E., Niehues, J. & Sommer, B. (2005). 
Vollaluminium-Zylinderkurbelgehäuse-Aluminium-
Zylinderlauflächen. Giesserei Praxis. 5, 167-176.  
[9] Scarlet, M. (2004). Power trio. Automotive Industries. 
August, 28-31. 
[10] Köhler, E. (1994). The KS LOKASIL process. Foundry 
International. March 1994, 3-4. 
[11] Mahle company information material.  
[12] KS Aluminium Technologie AG, Kolbenschmidt-Pierburg 
division information material. 
[13] Heusler, L., Feikus, F.J. & Otte, M.O. (2001). Alloy and 
casting process optimization for engine block application. 
AFS Transactions. 109, 443-451.  
[14] Prasad, B.K. & Vengneswaran, K. (1998). Sliding wear 
behavior of some Al-Si alloys. Role shape and size of Si 
particle and test conditions. Metallurgical and Materials 
Trans. A. 29A, 2747–2752. 
[15] Tomida, S., Nakata, K., Shibata, S., Zenkoui, J. & Sai, S. 
(2003). Improvement in wear resistance of hypereutectic Al-
Si cast alloy by laser surface remelting. Surface and Coating 
Technology. 169-170, 468-471. 
[16] Orłowicz, A.W. & Mróz, M. (2004). The effect of the arc 
welding process on the fusion surface layer on C-355 alloy 
casting. Archives of Foundry. 4, 2/11. 65-70. (in Polish) 
[17] Orłowicz, A.W. & Mróz, M. (2003). AK 7 alloy with surface 
layer refined by rapid crystallization. Archives of Foundry. 
3(7), 275-282. (in Polish) 
 
 


Combustion Engine Cylinder Liners Made of Al-Si Alloys

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=4FAC0379F23D0FC7A7D5C665510A5C42?doi=10.1.1.1037.2826&rep=rep1&type=pdf

Combustion Engine Cylinder Liners Made of Al-Si Alloys

Abstract

Similar works

Full text

Available Versions

CiteSeerX