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Wear and abrasion of cast Al-Alumina particle composites
Wear, 77 (1982) 295 - 302
WEAR AND ABRASION COMPOSITES
295
OF CAST Al-ALUMINA
PARTICLE
M. K. SURAPPA, S. V. PRASAD and P. K. ROHATGI Regional Research Laboratory Trivandrum 695019 (India)
(Council of Scientific and Industrial Research),
(Received February 16, 1981; in revised form October 26, 1981)
Summary
Wear rates for cast aluminium and Al-Si alloys containing up to 5 wt.% -r-AlaO, particles (100 pm size) were determined under conditions of adhesive wear and abrasive wear against a hardened steel disc and an alumina abrasive cloth sheet respectively. The adhesive wear rate of aluminium containing 5 wt.% AlaOs dispersions is similar to that of Al-11.8Si eutectic alloy and slightly higher than that of Al-16Si hypereutectic alloy. Al3wt.%AlsOa and Al-5wt.%Al,Os composites perform better than Al-11.8Si and Al-16Si hypereutectic alloys under abrasive wear conditions. Al-11.8Si and Al-16Si alloys have a lower abrasive wear resistance than pure aluminium. The results indicate that AlsOa particles can be used as a substitute for silicon as the hard dispersed phase in aluminium for wear-resistant and abrasion-resistant applications.
1. Introduction
Metallurgical techniques have been successfully employed to produce aluminium and aluminium-based alloys filled with hard ceramic particles such as alumina (AlaO,), silica (SiOa) and silicon carbide (Sic) [ 1] as well as soft particles such as graphite [6 - lo] and mica [11].The incorporation of ceramic particles such as AlaOs and SiOa in aluminium [1, 51 increases strength and hardness but lowers ductility. Sato and Mehrabian [3] have reported that composites of aluminium alloys containing 10 wt.% or more of SIC!, Si3N4, AlaOs, glass and silica sand prepared by compocasting techniques wear less than the pure matrix alloy when tested in a pin on disc apparatus. Although cast Al-ceramic particulate composites are primarily developed as antifriction and antiabrasion materials, no systematic investigation of wear properties under abrasive conditions has been reported. On the basis of difficulties encountered during machining, Badia [I] suggested that these 0043-1648/82/0000-0000/$02.75
0 Elsevier Sequoia/Printed in The Netherlands
296
composites may possess high abrasion resistance. The wear properties of AlSi alloys and Al-AlsOs composites containing up to 5 wt.% AlsOs particles under adhesive and abrasive conditions were investigated against steel discs and aluminium oxide abrasive cloth sheets respectively. The main objective of the investigation was the development of a cast Al-AlsOs particle composite with adhesive and abrasive wear properties comparable with Al-Si alloys. 2. Experimental
details
Alumina powder (r-Also,) from Sarabhai Chemicals was sieved, and the - 100 to + 300 sieve fraction was used as the filler material. Commercially pure aluminium and Al-11.8Si eutectic alloy were used as matrix materials. The alumina powder was preheated to 800 “C just before incorporation in the liquid metal. The composites were prepared by adding the predetermined quantity of Al,Os powder to the liquid metal or alloy at 800 “C whilst stirring above the liquidus to create a vortex. Good dispersions can be achieved by this vortex method [9 - 111. The composite melts were later cast into cast iron moulds and air cooled. Specimens were machined from the cast ingots for wear and abrasion studies. AlaOs contents were analysed chemically. Specimens 10 mm in diameter and 10 mm in length were used for adhesive wear testing using a lapping machine (Fig. 1). Experiments were carried out under dry conditions by sliding the sample under an applied load of 20 N on a steel disc 150 mm in diameter (hardness, 57 HRC). Before each experiment, the steel disc was ground to a surface finish of 0.3 pm centreline average. A fixed track diameter of 124 mm was used in all tests, which were of 10 min duration. Each test was run on a fresh track by changing the disc. Samples were tested three times at each composition and the average value was taken. For these conditions, the sliding velocity and sliding distance are 5.48 m s-l and 2545 m respectively.
_~zz$*P,
Fig. 1. Schematic diagram of adhesive wear apparatus.
The apparatus used for abrasive wear studies (Fig. 2(a)) consists of a friction drum which is rotated about a horizontal axis, a spindle and a rotating shaft. A sheet of alumina cloth was fixed to the friction drum and the sample was fixed to the rotating shaft. When the machine is switched on, the specimen is automatically brought into contact with the abrasive sheet which covers the rotating friction drum. Figure 2(b) shows a scanning elec-
(a) Fig, 2. (a) Abrasive wear testing machine; (b) SEM photograph of typical 80 grit alumina cloth sheet used in abrasive wear studies (magnification, 14X).
tron micrograph of 80 grit alumina abrasive sheet. The specimen traverses from one end of the drum to the other, which corresponds to a path length of 40 m.
3. Results and discussion 3.1. Adhesive wear Adhesive wear rates for aluminium, Al-11.8Si eutectic alloy and Al16Si hypereutectic alloy with Al,Os dispersions are shown in Fig. 3. Some mechanical properties of the composites and base alloys are given in Table 1. From Fig. 3, pure aluminium exhibits much higher wear than both of the Al-Si alloys and the wear rates of both aluminium and Al-Si alloys decrease with the addition of AlsOs particles. Figure 4 shows that the AlsOs filler particles were not pulled out of the matrix during the wear process. Earlier work on the wear of Al-Si alloys on steel discs [12, 131 has shown that the wear rate of Al-Si alloys is not a linear function of load as stated by the adhesive wear law [ 141. Shivnath et al. [ 12 ] reported that, a, low loads, wear of AI-Si alloys occurs by spalling of the oxide layer which separates the aluminium alloy and the steel disc. This process was described as oxidative wear and the wear rates were in the region lo-* - lo-’ cm3 cm-‘. Comparison of the present wear rates with those reported by Shivnath et al. [ 121 indicates that the present experimental conditions could well lead to mild oxidative wear. The results also show that the adhesive wear of Al5wt.%A1,03 composite is lower than that of Al-11.8Si eutectic alloy and only marginally higher than that of Al-16Si alloy. Adhesive wear resistance (the inverse of the wear rate) of matrix alloys and composites is plotted against hardness in Fig. 5. The wear resistance of Al-Si alloys increases linearly with hardness. However, the wear resistance versus hardness curve for composites deviates from linearity. Composites show a higher wear resistance than Al-Si alloys of similar hardness. There-
I
1
IO Weight
20
percent
I
I
30 Alumina
t
4.0
50
Fig. 3. Adhesive wear rates of ~umin~um and Al-Si alloy composites containing Al203 particles: 0, Al-A120,; 0, Al-11.8Si-Al,Os; A, Al-16Si-A1203. TABLE 1 Mechanical properties of cast Al-Al,03 Composition
Ultimate tensile strength (MN m-‘)
and Al-11.8Si-A1203
particle composites
Percentage elongation to break in tension
Hardness (HB)
Charpy impact strength (X lo* J m-‘)
Density (x lo3 kg m-3)
27
80
2.70
Al
77
37.5
A1-3wt.%Alz03
95
18.0
37
30
2.65
Al-5wt.%A1203
73
5.4
48
12
2.61
160
6.0
55
8
2.66
Al-11.8Si3wt.%Al203
125
2.8
62
2
2.63
Al-16Si alloy
135
4.4
72
4
2.63
Al-11.8Si
alloy
fore the expression relating wear resistance and hardness is not obeyed for composites cont~ning A1,03, which is much harder than the steel disc against which specimens were worn.
Hardness
Fig. 4. Worn-out surface of Al-Bwt.%AlgOa (Magnification, 68X.)
(BHN)
-
composite sample (after adhesive wear test).
Fig. 5. Variation in adhesive wear resistance with hardness: 0, aluminium alloys; Al203 composites.
q, Al-
3.2. Abrasive wear Abrasive wear rates for aluminium and for Al-Si alloys and their composites are shown in Fig. 6. The material removed per unit length of travel is directly proportional to the applied load for both the matrix alloys and the 3.00 2.75 2.50 2.25 ,E “E
200
i
E i
I .75
F L
1.50 t
5
I
.; L <
1.00
25
0.75
0
I
2
3
4 Applied
5 load,
c N
7
Fig. 6. Abrasive wear rates of Al-Al203 0, Al-3wt.%AlgOa; 0, Al-5wt.%A1203;4 16Si.
8
9
IO
and Al-11.8Si-A1203 composites: 0, aluminium; Al-11.8Si;A, Al-11.8Si-3wt.%AlgO,; w, Al-
300
composites. The abrasive wear rates of Al-4 alloys are slightly higher than that of pure aluminium. For convenience, a term “relative wear of composites”, which is defined as the wear rate of composite divided by the wear rate of matrix ahoy, has been adopted. Table 2 shows that the relative wear rate of Al-3wt.%AlsOs composite is less than unity at all loads. However, the TABLE 2 Relative wear rates of composites (abrasive wear) Material
A1-3wt.%Al&+j Al-5wt.%Al*03 Al-11.8Si-3wt.%A1203
Relative wear rates under the following loads 5N
10N
0.79 0.92 1.01
0.96 1.01 1.17
Fig. 7. Partially abraded surfaces showing isolated wear tracks (applied load, 1000 N): (a) aluminium; (b) A&-11.8Si aifoy; (c) Al-11.8Si alloy. (Magnifications: (a) 204x; (b) 204x; (c) 680x.)
301
relative wear rate of this composite increased from 0.79 to 0.96 when the load increased from 5 to 10 N. When the AlaOs content was increased from 3 to 5 wt.%, the relative wear rate increased from 0.79 to 0.92 under a 5 N load and from 0.96 to 1.01 under a 10 N load. With AI-11.8Si alloy composites, the relative wear rate is greater than unity under all loads and increases with increase in load. Figure 7 shows the abraded surfaces of aluminium and Al-11.8Si eutectic alloy which had been initially polished and abraded for a short duration of about 10 s to allow observation of the nature of isolated abrasive wear tracks. The abrasive wear track in pure aluminium (Fig. 7(a)) has a ploughed appearance with material displaced to the sides of the track. There is no build-up of material on the sides of the wear track of Al-11.8Si alloy (Fig. 7(b)). However, a magnified scanning electron microscopy (SEM) picture of the wear track in Al-11.8Si alloy shows that there is a tendency for chipping to occur across the track. Figure 8 shows the fully abraded surface of Al-11.8Si alloy. Material is removed as flakes, Figure 9 shows that the abraded surface of Al-&vt.%Al,Oa composite exhibits evidence of chipping similar to that in the Al-11.8Si alloy. A change in the mechanism of wear from ploughing to chipping could be responsible for higher wear rates of Al-Si alloys and Al-Eiwt.%Al,O, composites compared with pure aluminium despite a substantial increase in hardness.
Fig. 8. Fully abraded Al-11.8Si
alloy. (Magnification,
Fig. 9. Partially abraded surface of Al-5wt.%AL&
2040X.)
composite. (Magnification, 204X.)
4. Conclusions (1) The adhesive wear rates of aluminium and A&11.8% and Al-16Si ahoy castings decrease with the addition of r-AlsO, particles 100 ym in size. With a 5 wt.% dispersion of Al,Os particles, the adhesive wear rate of
302
aluminium is comparable with that of Al-11.8Si eutectic and Al-16Si hypereutectic alloys. (2) Also, the abrasive wear rate of Al-5wt.%Al,Os is lower than the abrasive wear rates of Al-11.8Si eutectic and Al-16Si hypereutectic alloys. (3) Abrasive wear tracks in pure aluminium exhibit material displacement by ploughing whereas those in Al-11.8Si eutectic alloy and Al5wt.%AlsOs composite exhibit chipping. (4) The results indicate that abundantly available inexpensive 100 km r-Also, particles dispersed in aluminium form a suitable substitute for expensive silicon to achieve improved wear properties.
Acknowledgments The authors thank Mr. K. Sukumaran for his assistance in performing the abrasive wear tests and Dr. R. V. Krishnan of NAL, Bangalore, and M. Krishna Raju of VSSC, Trivandrum, for help with the SEM studies.
References 1 2 3 4 5 6 7 8 9 10 11 12 13 14
F. A. Badia, Am. Foundrymen’s Sot. Trans., 79 (1971) 347. B. C. Pai, S. Ray, K. V. Prabbakar and P. K. Rohatgi, Mater. Sci. Eng., 24 (1976) 31. A. Sato and R. Mehrabian, Metall. Trans., 78 (1976) 443. M. K. Surappa, Ph.D. Thesis, Indian Institute of Science, Bangalore, 1979. P. K. Rohatgi, B. C. Pai and P. C. Panda, J. Mater. Sci., 14 (1979) 2277. F. A. Badia and P. K. Rohatgi, Am. Foundrymen’s Sot. Trans., 77 (1969) 402. B. C. Pai and P. K. Rohatgi, Trans. Indian Inst. Met., 27 (1974) 97. B. C. Pai and P. K. Rohatgi, J. Mater. Sci., 13 (1978) 329. M. K. Surappa and P. K. Rohatgi, Met. Technol., 5 (1978) 358. B. P. Krishnan, H. R. Shetty and P. K. Rohatgi, Am. Foundrymen’s Sot. Trans., 84 (1976) 73. Deonath, R. T. Bhat and P. K. Rohatgi, J. Mater. Sci., 15 (1980) 1241. R. Shivnath, P. K. Sengupta and T. S. Eyre, Br. Foundrymen, 70 (1977) 349. T. Clarke and A. D. Sarkar, Wear, 54 (1979) 7. E. Rabinowicz, Friction and Wear of Materials, Wiley, New York, 1965.
WEAR AND ABRASION COMPOSITES
295
OF CAST Al-ALUMINA
PARTICLE
M. K. SURAPPA, S. V. PRASAD and P. K. ROHATGI Regional Research Laboratory Trivandrum 695019 (India)
(Council of Scientific and Industrial Research),
(Received February 16, 1981; in revised form October 26, 1981)
Summary
Wear rates for cast aluminium and Al-Si alloys containing up to 5 wt.% -r-AlaO, particles (100 pm size) were determined under conditions of adhesive wear and abrasive wear against a hardened steel disc and an alumina abrasive cloth sheet respectively. The adhesive wear rate of aluminium containing 5 wt.% AlaOs dispersions is similar to that of Al-11.8Si eutectic alloy and slightly higher than that of Al-16Si hypereutectic alloy. Al3wt.%AlsOa and Al-5wt.%Al,Os composites perform better than Al-11.8Si and Al-16Si hypereutectic alloys under abrasive wear conditions. Al-11.8Si and Al-16Si alloys have a lower abrasive wear resistance than pure aluminium. The results indicate that AlsOa particles can be used as a substitute for silicon as the hard dispersed phase in aluminium for wear-resistant and abrasion-resistant applications.
1. Introduction
Metallurgical techniques have been successfully employed to produce aluminium and aluminium-based alloys filled with hard ceramic particles such as alumina (AlaO,), silica (SiOa) and silicon carbide (Sic) [ 1] as well as soft particles such as graphite [6 - lo] and mica [11].The incorporation of ceramic particles such as AlaOs and SiOa in aluminium [1, 51 increases strength and hardness but lowers ductility. Sato and Mehrabian [3] have reported that composites of aluminium alloys containing 10 wt.% or more of SIC!, Si3N4, AlaOs, glass and silica sand prepared by compocasting techniques wear less than the pure matrix alloy when tested in a pin on disc apparatus. Although cast Al-ceramic particulate composites are primarily developed as antifriction and antiabrasion materials, no systematic investigation of wear properties under abrasive conditions has been reported. On the basis of difficulties encountered during machining, Badia [I] suggested that these 0043-1648/82/0000-0000/$02.75
0 Elsevier Sequoia/Printed in The Netherlands
296
composites may possess high abrasion resistance. The wear properties of AlSi alloys and Al-AlsOs composites containing up to 5 wt.% AlsOs particles under adhesive and abrasive conditions were investigated against steel discs and aluminium oxide abrasive cloth sheets respectively. The main objective of the investigation was the development of a cast Al-AlsOs particle composite with adhesive and abrasive wear properties comparable with Al-Si alloys. 2. Experimental
details
Alumina powder (r-Also,) from Sarabhai Chemicals was sieved, and the - 100 to + 300 sieve fraction was used as the filler material. Commercially pure aluminium and Al-11.8Si eutectic alloy were used as matrix materials. The alumina powder was preheated to 800 “C just before incorporation in the liquid metal. The composites were prepared by adding the predetermined quantity of Al,Os powder to the liquid metal or alloy at 800 “C whilst stirring above the liquidus to create a vortex. Good dispersions can be achieved by this vortex method [9 - 111. The composite melts were later cast into cast iron moulds and air cooled. Specimens were machined from the cast ingots for wear and abrasion studies. AlaOs contents were analysed chemically. Specimens 10 mm in diameter and 10 mm in length were used for adhesive wear testing using a lapping machine (Fig. 1). Experiments were carried out under dry conditions by sliding the sample under an applied load of 20 N on a steel disc 150 mm in diameter (hardness, 57 HRC). Before each experiment, the steel disc was ground to a surface finish of 0.3 pm centreline average. A fixed track diameter of 124 mm was used in all tests, which were of 10 min duration. Each test was run on a fresh track by changing the disc. Samples were tested three times at each composition and the average value was taken. For these conditions, the sliding velocity and sliding distance are 5.48 m s-l and 2545 m respectively.
_~zz$*P,
Fig. 1. Schematic diagram of adhesive wear apparatus.
The apparatus used for abrasive wear studies (Fig. 2(a)) consists of a friction drum which is rotated about a horizontal axis, a spindle and a rotating shaft. A sheet of alumina cloth was fixed to the friction drum and the sample was fixed to the rotating shaft. When the machine is switched on, the specimen is automatically brought into contact with the abrasive sheet which covers the rotating friction drum. Figure 2(b) shows a scanning elec-
(a) Fig, 2. (a) Abrasive wear testing machine; (b) SEM photograph of typical 80 grit alumina cloth sheet used in abrasive wear studies (magnification, 14X).
tron micrograph of 80 grit alumina abrasive sheet. The specimen traverses from one end of the drum to the other, which corresponds to a path length of 40 m.
3. Results and discussion 3.1. Adhesive wear Adhesive wear rates for aluminium, Al-11.8Si eutectic alloy and Al16Si hypereutectic alloy with Al,Os dispersions are shown in Fig. 3. Some mechanical properties of the composites and base alloys are given in Table 1. From Fig. 3, pure aluminium exhibits much higher wear than both of the Al-Si alloys and the wear rates of both aluminium and Al-Si alloys decrease with the addition of AlsOs particles. Figure 4 shows that the AlsOs filler particles were not pulled out of the matrix during the wear process. Earlier work on the wear of Al-Si alloys on steel discs [12, 131 has shown that the wear rate of Al-Si alloys is not a linear function of load as stated by the adhesive wear law [ 141. Shivnath et al. [ 12 ] reported that, a, low loads, wear of AI-Si alloys occurs by spalling of the oxide layer which separates the aluminium alloy and the steel disc. This process was described as oxidative wear and the wear rates were in the region lo-* - lo-’ cm3 cm-‘. Comparison of the present wear rates with those reported by Shivnath et al. [ 121 indicates that the present experimental conditions could well lead to mild oxidative wear. The results also show that the adhesive wear of Al5wt.%A1,03 composite is lower than that of Al-11.8Si eutectic alloy and only marginally higher than that of Al-16Si alloy. Adhesive wear resistance (the inverse of the wear rate) of matrix alloys and composites is plotted against hardness in Fig. 5. The wear resistance of Al-Si alloys increases linearly with hardness. However, the wear resistance versus hardness curve for composites deviates from linearity. Composites show a higher wear resistance than Al-Si alloys of similar hardness. There-
I
1
IO Weight
20
percent
I
I
30 Alumina
t
4.0
50
Fig. 3. Adhesive wear rates of ~umin~um and Al-Si alloy composites containing Al203 particles: 0, Al-A120,; 0, Al-11.8Si-Al,Os; A, Al-16Si-A1203. TABLE 1 Mechanical properties of cast Al-Al,03 Composition
Ultimate tensile strength (MN m-‘)
and Al-11.8Si-A1203
particle composites
Percentage elongation to break in tension
Hardness (HB)
Charpy impact strength (X lo* J m-‘)
Density (x lo3 kg m-3)
27
80
2.70
Al
77
37.5
A1-3wt.%Alz03
95
18.0
37
30
2.65
Al-5wt.%A1203
73
5.4
48
12
2.61
160
6.0
55
8
2.66
Al-11.8Si3wt.%Al203
125
2.8
62
2
2.63
Al-16Si alloy
135
4.4
72
4
2.63
Al-11.8Si
alloy
fore the expression relating wear resistance and hardness is not obeyed for composites cont~ning A1,03, which is much harder than the steel disc against which specimens were worn.
Hardness
Fig. 4. Worn-out surface of Al-Bwt.%AlgOa (Magnification, 68X.)
(BHN)
-
composite sample (after adhesive wear test).
Fig. 5. Variation in adhesive wear resistance with hardness: 0, aluminium alloys; Al203 composites.
q, Al-
3.2. Abrasive wear Abrasive wear rates for aluminium and for Al-Si alloys and their composites are shown in Fig. 6. The material removed per unit length of travel is directly proportional to the applied load for both the matrix alloys and the 3.00 2.75 2.50 2.25 ,E “E
200
i
E i
I .75
F L
1.50 t
5
I
.; L <
1.00
25
0.75
0
I
2
3
4 Applied
5 load,
c N
7
Fig. 6. Abrasive wear rates of Al-Al203 0, Al-3wt.%AlgOa; 0, Al-5wt.%A1203;4 16Si.
8
9
IO
and Al-11.8Si-A1203 composites: 0, aluminium; Al-11.8Si;A, Al-11.8Si-3wt.%AlgO,; w, Al-
300
composites. The abrasive wear rates of Al-4 alloys are slightly higher than that of pure aluminium. For convenience, a term “relative wear of composites”, which is defined as the wear rate of composite divided by the wear rate of matrix ahoy, has been adopted. Table 2 shows that the relative wear rate of Al-3wt.%AlsOs composite is less than unity at all loads. However, the TABLE 2 Relative wear rates of composites (abrasive wear) Material
A1-3wt.%Al&+j Al-5wt.%Al*03 Al-11.8Si-3wt.%A1203
Relative wear rates under the following loads 5N
10N
0.79 0.92 1.01
0.96 1.01 1.17
Fig. 7. Partially abraded surfaces showing isolated wear tracks (applied load, 1000 N): (a) aluminium; (b) A&-11.8Si aifoy; (c) Al-11.8Si alloy. (Magnifications: (a) 204x; (b) 204x; (c) 680x.)
301
relative wear rate of this composite increased from 0.79 to 0.96 when the load increased from 5 to 10 N. When the AlaOs content was increased from 3 to 5 wt.%, the relative wear rate increased from 0.79 to 0.92 under a 5 N load and from 0.96 to 1.01 under a 10 N load. With AI-11.8Si alloy composites, the relative wear rate is greater than unity under all loads and increases with increase in load. Figure 7 shows the abraded surfaces of aluminium and Al-11.8Si eutectic alloy which had been initially polished and abraded for a short duration of about 10 s to allow observation of the nature of isolated abrasive wear tracks. The abrasive wear track in pure aluminium (Fig. 7(a)) has a ploughed appearance with material displaced to the sides of the track. There is no build-up of material on the sides of the wear track of Al-11.8Si alloy (Fig. 7(b)). However, a magnified scanning electron microscopy (SEM) picture of the wear track in Al-11.8Si alloy shows that there is a tendency for chipping to occur across the track. Figure 8 shows the fully abraded surface of Al-11.8Si alloy. Material is removed as flakes, Figure 9 shows that the abraded surface of Al-&vt.%Al,Oa composite exhibits evidence of chipping similar to that in the Al-11.8Si alloy. A change in the mechanism of wear from ploughing to chipping could be responsible for higher wear rates of Al-Si alloys and Al-Eiwt.%Al,O, composites compared with pure aluminium despite a substantial increase in hardness.
Fig. 8. Fully abraded Al-11.8Si
alloy. (Magnification,
Fig. 9. Partially abraded surface of Al-5wt.%AL&
2040X.)
composite. (Magnification, 204X.)
4. Conclusions (1) The adhesive wear rates of aluminium and A&11.8% and Al-16Si ahoy castings decrease with the addition of r-AlsO, particles 100 ym in size. With a 5 wt.% dispersion of Al,Os particles, the adhesive wear rate of
302
aluminium is comparable with that of Al-11.8Si eutectic and Al-16Si hypereutectic alloys. (2) Also, the abrasive wear rate of Al-5wt.%Al,Os is lower than the abrasive wear rates of Al-11.8Si eutectic and Al-16Si hypereutectic alloys. (3) Abrasive wear tracks in pure aluminium exhibit material displacement by ploughing whereas those in Al-11.8Si eutectic alloy and Al5wt.%AlsOs composite exhibit chipping. (4) The results indicate that abundantly available inexpensive 100 km r-Also, particles dispersed in aluminium form a suitable substitute for expensive silicon to achieve improved wear properties.
Acknowledgments The authors thank Mr. K. Sukumaran for his assistance in performing the abrasive wear tests and Dr. R. V. Krishnan of NAL, Bangalore, and M. Krishna Raju of VSSC, Trivandrum, for help with the SEM studies.
References 1 2 3 4 5 6 7 8 9 10 11 12 13 14
F. A. Badia, Am. Foundrymen’s Sot. Trans., 79 (1971) 347. B. C. Pai, S. Ray, K. V. Prabbakar and P. K. Rohatgi, Mater. Sci. Eng., 24 (1976) 31. A. Sato and R. Mehrabian, Metall. Trans., 78 (1976) 443. M. K. Surappa, Ph.D. Thesis, Indian Institute of Science, Bangalore, 1979. P. K. Rohatgi, B. C. Pai and P. C. Panda, J. Mater. Sci., 14 (1979) 2277. F. A. Badia and P. K. Rohatgi, Am. Foundrymen’s Sot. Trans., 77 (1969) 402. B. C. Pai and P. K. Rohatgi, Trans. Indian Inst. Met., 27 (1974) 97. B. C. Pai and P. K. Rohatgi, J. Mater. Sci., 13 (1978) 329. M. K. Surappa and P. K. Rohatgi, Met. Technol., 5 (1978) 358. B. P. Krishnan, H. R. Shetty and P. K. Rohatgi, Am. Foundrymen’s Sot. Trans., 84 (1976) 73. Deonath, R. T. Bhat and P. K. Rohatgi, J. Mater. Sci., 15 (1980) 1241. R. Shivnath, P. K. Sengupta and T. S. Eyre, Br. Foundrymen, 70 (1977) 349. T. Clarke and A. D. Sarkar, Wear, 54 (1979) 7. E. Rabinowicz, Friction and Wear of Materials, Wiley, New York, 1965.