“Wear Characterization of Fly Ash with Various Binders and Reinforcement Materials”

“Wear Characterization of Fly Ash with Various Binders and Reinforcement Materials”

Wear Characterization of Fly Ash with Various Binders and Reinforcement Materials

Sharanabasappa Bolashetty1, Bhargavi A2, Prashantha Kumar S T3

1 Department of Mechanical Engineering, Vijaya Vittala Institute of Technology, Bangalore

2 Department of Mechanical Engineering, Vijaya Vittala Institute of Technology, Bangalore

3Assistant Professor, Department of Mechanical Engineering, Vijaya Vittala Institute of Technology, Bangalore.

Abstract:- The fly ash is being produced by the combustion of coal from the thermal power plants. At present an enormous amount of fly ash is being accumulated as waste by thermal power plants throughout the world. To mitigate this problem fly ash has been mixed with different reinforcement materials and binders by varying the percentages and prepare composite materials. The fabricated composites were subjected to hardness test and wear test. The samples which have higher hardness with no cracks on the surface were subjected for wear tes. On the basis of the results of hardness and wear tests conducted, the samples which show better results during the test were sent for microstructure analysis.

1. INTRODUCTION

   The composite material can be defined as two phase material consisting of a mixture of combination of two or more micro constituents insoluble in each other and differing in form and or in material composition. These materials can be prepared by putting two or more dissimilar material in such way that they function mechanically as a single unit. The properties of such materials differ from those of their constituents. These materials may have a hard phase embedded in a soft phase or vice versa. Normally in the composite material have a hard phase in the soft ductile matrix where the hard phase act as a reinforcing agent increase the strength and modulus of elasticity, and soft phase act as matrix material.

   The composite often show the best qualities of their constituent materials and usually exhibits some properties that neither constitutes processes. Formulation design for composite friction material is a well known problem of multi criteria optimization that involves the assessment of various performance defining attributes such as wear, fade etc[14]. Since fly ash has the potential to improve the abrasion resistance and porosity of the material while simultaneously enhancing the specific performance it could be fundamentally expected that their incorporation would possibly cater to various functional roles which otherwise are expected from a set of fillers as ingredients. The successful incorporation of fly ash or fly ash derivatives into friction material formulations could greatly reduce the cost of the friction material, i.e. 5060% assuming total filler fraction is substituted. Several patents highlighting the possible use of fly ash as a key ingredient in friction material sector are already reported though they remain

   obscure from the general material researchers as their outcomes are highly sensitive from techno-commercial and ecological point of view. However, the partial/complete realization of such an ideology of utilization of industrial waste conforming to green norms conceptually depend on the performance assessment and its fluctuation due to variation in the nature of the waste material which may vary widely as the grades of coals. Hence, to address this problem of performance alterations of compositional origin and precisely due to change in the nature of added fly ash into friction composites is of key concern. Such comprehensions at the performance level by selecting one type of fly ash as filler may be realized by theoretical manipulation of the performance parameters via the application of several operation research and statistical tools which may enable the assessment of the influences.

2. EXPERIMENTAL PROCEDURE

   1. Materials

      The materials used are fly ash and vermiculite as filler materials, steel wool, iron oxide as abrasive materials, natural graphite as a lubricant, ceramic fiber, mineral fiber, and cellulose fiber as reinforcements, resin, cashew nut oil and NC thinner as binders. Fly ash was used as a filler material and about 30-40% fly ash was successfully incorporated with friction materials.

   2. Experimental details.

   The basic methodology used was powder metallurgy technique. The required amounts of different powders to be mixed were weighed using a digital weighing machine. The various constituents were mixed thoroughly for about 15 minutes. The die used was made of E32 hard steel. After the mixing process the mixture was filled to the die. The die was kept between the jaws of the universal testing machine and a pressure of 30KN was applied to get a compacted sample. The samples were heated to temperature gradually increasing from 70 0c to 150 0c in an oven for about 30 minutes. The samples were then cut and grinded to a standard size.

   100

   90

   Hardness

   Hardness

   80

   70

   60

   50

   40

   30

   20

   10

   0

   36 37 38 39 40 41 45 46 53 54 55 56

   Sample Number

   Figure 1; E32 Hard steel die and plunger

   The samples were then subjected to hardness test using Rockwell hardness tester (B scale). The samples which show higher hardness value were selected and the wear test was conducted. During the wear test few samples were failed due to cracks on the surface and low bonding strength. Totally 20 samples were subjected to wear test, out of 20 samples 10 samples showed good results, the wear rate for the samples were calculated and graphs are plotted. Based on the wear rate the samples showed decreasing wear rates with increasing of time were selected and microstructure analysis was done for few samples.

3. RESULTS AND DISCUSSIONS

   1. Hardness test

      120

      100

      80

      60

      40

      20

      0

      1 2 4 5 6 7 9 10 15 15 22 23 24 34 35

      Sample Number

      120

      100

      80

      60

      40

      20

      0

      1 2 4 5 6 7 9 10 15 15 22 23 24 34 35

      Sample Number

      Hardness

      Hardness

      The samples prepared were subjected to hardness test based on the hardness of the samples they were subjected to wear test. The samples which show higher hardness value were selected and the wear test was conducted.

      Figure: 2a; Hardness test results

      Figure: 2b; Hardness test results

   2. Wear Test Results

      The variations in wear with time were found using a pin on disc wear testing machine. Before and after the wear test the weights of each specimen were noted down to determine the volumetric wear rate. A load of 10kg was applied through the lever arm. The test was conducted for different sliding distance (5, 10, 15 minutes) and the wear rate for the samples were calculated and the graphs are plotted for time versus wear rate as shown below. The volumetric wear rate was calculated by using the following formula,

      = ( ) ×

      ×

      The unit is mm3/Nm

      Sliding distance was calculated by using the formula,

      = /

      Where, r is the radius of track on disc in meter = 42×10-3m N is the rotating speed of the disc in rpm = 450 rpm

      9

      8

      Wear rate (*10-5 mm3 /Nm)

      Wear rate (*10-5 mm3 /Nm)

      7

      6

      5

      4

      3

      2

      1

      0

      0 10 20

      Time (minutes)

      Figure: 3a; volunetric wear rate results

      sample 4

      sample 5

      sample 22

      sample 24

      analysis of the samples revealed uniform and consistent wear and generation of friction layer uniformly distributed over the entire contact surface. This could explain the stable co-efficient of friction values and the low wear rate.

      9

      8

      7

      6

      5

      4

      3

      2

      1

      0

      9

      8

      7

      6

      5

      4

      3

      2

      1

      0

      sample 45

      sample 45

      sample 46

      sample 53

      sample 54

      sample 56

      0

      sample 46

      sample 53

      sample 54

      sample 56

      0

      Wear rate (*10-5 mm3

      /Nm)

      Wear rate (*10-5 mm3

      /Nm)

      In figure 3a the wear rates for all the samples decreased gradually and finally increase however for one of the sample the wear rate goes on decreasing and showed a good result of wear rate.

      10

      Time (minutes)

      10

      Time (minutes)

      20

      20

      Figure: 3b; volunetric wear rate results

      In the fig 3b, for the samples 54 and 56, the wear rate decreased initially and increased later with time. For the samples 45, 46 and 53 the wear rate goes on decreasing so that the wear rate for those materials were very less.

   3. Micro Structure Analysis

      The specimens were first subjected to platinum coating and then loaded in to the SEM machine. At the beginning the vacuum state was achieved and then the electron beam was made to focus on the specimen. Images at 100X magnifications were obtained. After the micro structure the EDAX analysis was done to find the elements in the specimens. The micro structure analyses for some of the specimens are as follows:

      It was noted from the SEM images (Fig. 4, 5 and 6) that steel wool and fiber materials were pulled out due to friction between disc and the friction material. Surface

      Figure: 4

      Figure: 5

      Figure: 6

      SEM micro structure for the samples at 100X magnification.

   4. EDAX Analysis

   Element	Element %	Sigma %	Atomic %
   O	39.33	4.36	61.57
   Al	9.15	1.68	8.50
   Si	12.99	1.92	11.58
   K	3.23	1.02	2.07
   Ca	2.60	0.96	1.62
   Fe	32.70	3.55	14.67
   Total	100.00		100.00

   Figure; 7

   Element	Element %	Sigma %	Atomic %
   O	44.14	3.08	67.09
   Al	6.71	1.23	6.05
   Si	12.69	1.37	10.99
   Fe	34.46	2.76	15.88
   Total	100.00		100.00

   Figure; 8

   Element	Element %	Sigma %	Atomic %
   O	47.69	3.98	68.71
   Al	5.50	1.42	4.70
   Si	14.47	1.88	11.87
   Ca	8.36	1.33	4.81
   Fe	23.98	3.09	9.90
   Total	100.00		100.00

   Figure; 9

   EDAX analysis results for the samples.

4. CONCLUSION

   The above study high lights that, as the hardness increases, wear decreases with the increase of binding materials and reinforcements. In some of the specimens wear increases slightly.

   It is seen that, the wear rate is a particular parameter based on the percentage of quantity of binding materials along with the reinforcements and the fly ash.

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1. Eriksson M. Friction and contact phenomena of disc brakes related to squeal. Comprehensive summaries of Uppsala dissertations from the Faculty of Science and Technology 537, ACTA Universitatis Upsaliensis, 2000.

2. Chan D, Stachowiak GW. Review of automotive brake friction materials. J Automob Eng Proc Inst Mech Eng 2004;218(Part D).

3. American Coal Ash Association. ACAA 2004 CCP survey, 2004.

4. Hee KW, Filip P. Performance of ceramic enhanced phenolic matrix brake lining materials for automotive brake linings. Wear 2005; 259:108896.

5. Gudmand-Hoyer, A. Bach, G. T. Neilsen, and Per Morgan (1999) Tribological properties ofautomotive disc brakes with solid lubricants, Wear, 232, pp. 168-175.

6. S. K. Rhee (1971) Wear of Metal-Reinforced Phenolic Resins, Wear, 18, pp. 471-477.

7. S. K. Rhee (1974) Wear Mechanisms for Asbestos-Reinforced Automotive Friction Materials, Wear, 29, pp. 391-393.

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