Wear 263 (2007) 604–608 Case study Wear resistance of thermally sprayed rotary tiller blades Satit Karoonboonyanan a , Vilas M. Salokhe a , Panadda Niranatlumpong b,∗ a Agricultural Systems and Engineering, School of Environment Resources and Development, Asian Institute of Technology (AIT), P.O. Box 4, Klong Luang, Patumthani 12120, Thailand b National Metal and Materials Technology Center, 114 Thailand’s Science Park, Pathumthani 12120, Thailand Received 28 August 2006; received in revised form 6 December 2006; accepted 10 December 2006 Available online 23 May 2007 Abstract A rotary tiller is an agricultural implement, popularly used to reduce the amount of time and labour spent in soil preparation. It can also be used to incorporate residue in a sugarcane field into the soil to increase the organic matter content. However, wear of rotary tiller blades is very high, especially in sandy soil, which significantly affects its working life. The objective of this study was to increase the useful life of the tiller blade in order to reduce the idle time required to replace the blade periodically during soil preparation. The objective was carried out by means of hard coatings, where the effect of the coatings on the wear damage and the wear characteristics of the rotary tiller blades were investigated. This study compared two different thermal spray coatings, namely HVOF-sprayed WC/Co and plasma-sprayed Al 2 O 3 –TiO 2 /NiAl, on carbon steel rotary tiller blades. A test was conducted on a 3.2-ha area of sugarcane field after harvesting. The soil condition during the time of the test was dry, hard and sandy. The test blades were arranged in the tiller using a randomized complete block design pattern to compensate for the blade position sensitivity in order to achieve meaningful data. The test result showed that the average wear rate of the uncoated blades was 0.86cm 3 /ha, while those of the WC/Co and the Al 2 O 3 coatings were 0.02 and 0.90, respectively. The wear rates of the WC/Co-coated blades were significantly lower than those of the uncoated blades, indicating a great improvement in the wear protection provided by the coatings. The Al 2 O 3 -coated blades, however, did not show superiority over the uncoated reference blades. Some chipping of the Al 2 O 3 coating was observed, which greatly contributed to the high wear rate. © 2007 Elsevier B.V. All rights reserved. Keywords: Rotary tiller; Wear in agricultural machinery; Sugar cane residue; Thermal sprayed coatings 1. Introduction Wear is the major reason that limit the durability of many agricultural tools. Agricultural soil-cutting tools have their own characteristics of wear, which are different from other types, since they interact with soils of various textures, moistures and other unpredictable conditions in the field. Among the soil- cutting agricultural tools currently used, the rotary tiller is one of the most promising pieces equipment, saving operating time and labour. The use of the rotary tiller in sugarcane fields has been developed to incorporate sugarcane residues after harvesting in order to increase organic matters in the soil and to avoid trash burning, which can help to conserve the agro-ecological system [1]. One rotary tillage may be equivalent to several conventional tillage operations. Although the rotary tiller is an energy and ∗ Corresponding author. Tel.: +66 2564 6500; fax: +66 2564 6401. E-mail address: panaddn@mtec.or.th (P. Niranatlumpong). time efficient pieces of equipment, rapid wear of the tiller blades, typically made from medium carbon steels, in certain conditions may restrict its use. Heat treatments are often carried out to pro- vide protection to the blades in order to lengthen the service life of the carbon steel blade and, hence, reduce the total cost of agricultural production. In practice, though, it is found that the heat treated blade may not provide satisfactory protection in harsh field conditions. High wear rate is still observed, resulting in routine blade replacement during tillage. The rotary tiller has been increasingly used for puddling in paddy fields and cultivation in other agricultural fields. How- ever, studies on wear of its blade as well as wear resistance of different surface treatments are scarce, although wear is the most important factor for predicting service life of a blade. Therefore, there is a need to study these aspects carefully. The surface of the tiller blade, which is normally heat treated by the manufacturer, can be further improved to achieve higher wear resistance and/or lower friction by several other surface engineering techniques such as enamel coating and flame spraying [2]. 0043-1648/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2006.12.072