Application to Ceramic Powder in Combustion Engine ... · PDF fileApplication to Ceramic Powder in Combustion Engine Components to Thermal Insulation Irahy Martins da Silva1, Sandro

Application to Ceramic Powder in Combustion Engine Components to Thermal Insulation

Irahy Martins da Silva1, Sandro Aparecido Baldacim2,

Oliverio Moreira Macedo Silva2, Cosme Roberto Moreira da Silva2

1CTA-IAE-ASA_P- Divisão de Motores e Propulsão 2CTA-IAE-AMR - Divisão de Materiais

Pça. Marechal do Ar Eduardo Gomes, 50 - Vila das Acácias São José dos Campos – SP - Cep: 12228-904

email : [email protected]

Keywords: Ceramic powder, alumina, diesel/querosene engine, plasma coating ABSTRACT. In a wide variety of applications, mechanical components have to operate under severe conditions, such as high load, speed or temperature and hostile chemical environment. Thus, ceramic coatings produced by thermal etching techniques are widely used for a range of industrial applications, to confer wear and erosion resistance, corrosion protection and thermal insulation. Thus, this work has as objective to deposition of the alumina ceramic powder by plasma etching in the combustion engine components (piston, valves, combustion camera), actuating such as thermal insulation to increase temperature in the combustion camera and consequently improvement of the efficiency and power. The ceramic-metal adhesion, thermal/mechanical and thermal insulation properties were evaluated by SEM and dynamometer tests, presenting promissory results related to performance and efficiency of the combustion engine recovered to ceramic powder material. I. INTRODUCTION

The rapid increase in fuel expenses, the decreasing supply of high-grade fuels on the market and environmental concerns stimulated research on more efficient engines with acceptable emission characteristics [1-2]. The state-of-art thermal barrier coatings (TBC) provide the potential for higher thermal efficiencies of the engine, improved combustion and reduced emissions. In addition, ceramics show better wear characteristics than conventional materials [3-4]. Lower heat rejection from the combustion chamber through thermally insulated components causes an increase in available energy that would increase the in-cylinder work and the amount of energy transported by the exhaust gases, which could be also utilized

The thermal barrier coatings used, for example, in airplane jet engine turbines provide a practical example where optimization of metal–ceramic interfaces is crucial. Similar materials technology is used in such diverse applications as coating the gas turbines of stationary power plants to creating protective outer coatings for the space shuttle. What all such applications have in common is the necessity of a protective coating designed to withstand the harsh temperature cycling and the potentially oxidative/corrosive operating environment [2; 5].

There are many combinations of metallic and nonmetallic materials that can combine to obtain increase of mechanical and physical properties [6-7]. This led scientists to study many new ceramic materials to meet increasing requirements and demands in various application areas. Advanced furnaces and heat engines played important roles in the success of the industrial revolution, while ceramic materials were essential for thermal insulation of various types of furnaces and engines [5; 8-10].

The Al2O3 ceramic powder is one of the materials utilized to improve the thermal insulation in components submitted a high temperature, which is light weight, chemically and thermally stable up to very high temperatures and easy to pack around the cell [11-12].

The technique plasma-sprayed ceramic coatings are used to protect metallic structural components from corrosion, wear, and erosion, and to provide lubrication and thermal insulation [13-14].

The necessity of the operational researches involving the combustion engine give rise to study and application of ceramic material in the internal wall of the combustion camera, considering the piston in the maximal point of the gas compression. The reduction of the pollution, occasioned by better burning of the mixture air-fuel, motivated to smaller heat retired of the combustion camera is obtained by ceramic material recover, actuating such as thermal insulation.

In this work, the utilization of the querosene fuel in combustion engine components has been studied and analyzed aiming to obtain a low cost alternative fuel. Meanwhile, the tests results in laboratories showed a high smoke degree indicating deficient burning of the querosene fuel, probably due to low temperature in combustion camera. Thus, this work has as objective the deposition of the alumina ceramic powder by plasma etching, in the combustion engine components, actuating such as thermal insulation to increase temperature in the combustion camera and consequently improvement of the efficiency and performance.

II. METHODS AND MATERIALS

In this work, the components of piston internal combustion engine, manufactured by Kubota

Tekko Brazil, was submitted a ceramic coating realized by CELMA laboratory, showed by Figures 1-2. The edge wall of the combustion camera, valves and piston were recovered with alumina (Al2O3) ceramic powder by plasma etching.

Figure 1. Combustion engine components recovered Al2O3 via plasma. The micrographs analysis, showing metal-ceramic adhesion and interface, were taken using

scanning electron microscope (SEM) before and after etching 3% Nital. The original engine and engine with ceramic coating were submitted to dynamometer tests, during 80 hours, aiming evaluated thermal/mechanical and thermal insulation properties of application ceramic coating.

Valves (gray cast iron)

Combustion camera (gray cast iron)

Al2O3 ceramic coating

Figura 2. Aspect of edge wall of the combustion camera (gray cast iron) with Al2O3 ceramic coating.

III. RESULTS AND DISCUSSIONS

The micrographs analysis obtained by scanning electron microscope (SEM), showed by

Figures 3-4, present the metal-ceramic homogenous and uniformly interface. These characteristics are factors important to demonstrate and evaluate thermal insulation efficiency.

After dynamometer tests, with engine submitted to chemical, thermal and mechanical vibration solicitations, observed the integrity of ceramic coating in metallic surface, evidencing the strong adhesion to metal-ceramic interface.

However, is fundamental the analysis more detailed of metal-ceramic interface by transmission electron microscope (TEM) coupled EDS, to evaluate the adhesion mechanisms activated and that materials are present in interface.

Figure 3. Photomicraghs showing Al2O3 ceramic coating in components of combustion engine (gray iron cast) homogenous and uniformly distributed.

Edge wall of the combustion camera with Al2O3 ceramic coating

Gray casti ron

Al2O3 ceramic coating

Gray casti ron

Al2O3 ceramic coating

Figure 4. Photomicraghs showing Al2O3 ceramic coating in components of combustion engine (gray iron cast) chemical etched 3% Nital.

The figure 5 show the smoke curves to combustion engine with and without ceramic coating.

Observed the reduction of the pollution (smoke), occasioned by ceramic coating application, actuating such as thermal insulation that promoted to burning more efficient of the mixture air-fuel, due to smaller heat retired of the combustion camera.

2

3

4

5

6

7

1200 1300 1400 1500 1600 1700 1800

Rotação (RPM)

Nív

el d

e Fu

maç

a

Querosene / com cerâmicaQuerosene / sem cerâmica

Figure 5 – Smoke curves to combustion engine with and without ceramic coating.

Thus, the reduction of the pollution (smoke) indicates a significant increase of the temperature in combustion camera, improving the performance and efficiency of combustion engine, particularly to querosene fuel.

Gray casti ron

Al2O3 ceramic coating

Gray casti ron

Al2O3 ceramic coating

IV. CONCLUSIONS

Observed by SEM that metal-ceramic interface homogenous and uniform, fundamental to efficiency of thermal insulation properties.

The dynamometer tests, when the engine was submitted to chemical, thermal and mechanical vibration solicitations, were important to observe the strong metal-ceramic adhesion. However, analysis by TEM will be fundamental to evaluate the adhesion mechanisms present.

The ceramic coating applied in combustion engine components, actuating such as thermal insulation, showed important and necessary. The reduction of pollution (smoke), due to ceramic coating, occasioned the significant increase of temperature in combustion camera, consequently, promoting to burning more efficient of mixture air-fuel, contributing to improve an efficiency and performance of combustion engine.

Therefore, the results obtained with ceramic coating application, related to improve of performance and efficiency of combustion engine, particularly to querosene fuel, are significant and promissors.

AKNOWLEDGEMENTS FAPESP – Fundação de Amparo a Pesquisa do Estado de São Paulo CTA/IAE/AMR – Divisão de Materiais CTA/IAE/ASA_P - Divisão de Motores e Propulsão REFERENCE [1] R.L. Jones, Combust. Sci. Technol. 129 (1997), 185-195. [2] G. Wochni, W. Splinder, J. Eng. Gas. Turbines 110 (1988), 482-502. [3] T. Hajwowski, Vacuum 65 (2002), 427-432. [4] T. Hajwowski, Proc ISAPS 2 (1999), 211-216. [5] L. Powlowski, The Science and Engineering of Thermal Spray Coatings, Wiley Sons, New York, 1995. [6] J.N. Fridlyander, I.H. Marshall, Ceramic and Carbon Matrix-Composites, Ed. Academician V.I. Trefilov - Chapman & Hall. London, 1995. [7] R. Warren, Ceramic-matrix Composites, Chapman and Hall, New York, 1992. [8] H. Herman, C.C. Berndt, H. Wang, Plasma-Sprayed Ceramic Coatings, in: J.B. Wachtman, R.A Haber (Eds.), Ceramic Films and Coatings, NJ, 1993. [9] D.A.J. Ramm, T.W. Clyne, A.J. Sturgeon, S. Dunkerton, Proc. 7th National Thermal Spray Conference, Boston, MA, June 1994, ASM International, 1994, pp. 239–243. [10] S.E. Hartfield-Wünsch, S.C. Tung, Proc. 7th National Thermal Spray Conference, Boston, MA, June 1994, ASM International, 1994, pp. 19–24. [11] K. Niemi, P. Sorsa, P. Vuoristo, T. Mäntylä, Proc. 7th National Thermal Spray Conference, Boston, MA, June 1994, ASM International, 1994, pp. 533–536. [12] K. Kamachi, M. Magome, K. Ueno, G. Ueno, T. Yoshioka, Proc. 3rd National Thermal Spray Conference, Long Beach, CA, May 1990, ASM International, 1991, pp. 497–501. [13] M.K. Hobbs, H. Reiter, Thermal Spray: Advances in Coatings Technology, ASM International, 1989, pp. 285–290. [14] R. Kingswell, D.S. Rickerby, K.T. Scott, S.J. Bull, Proc. 3rd National Thermal Spray Conference, Long Beach, CA, May 1990, ASM International, 1991, pp. 179–185.