Wear resistance of thermally sprayed rotary tiller blades

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 Al2O3–TiO2/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 0.86 cm3/ha, while those of the WC/Co and the Al2O3 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 Al2O3-coated blades, however, did not show superiority over the uncoated reference blades. Some chipping of the Al2O3 coating was observed, which greatly contributed to the high wear rate.