Wear Resistance Improvement of Cemented Tungsten Carbide Deep-Hole Drills after Ion Implantation.

Dmitrij Morozow,Jacek Caban,Jerzy Zagórski,Zbigniew Krzysiak,Marcin Pisarek,Leszek Chałko,Marek Łagodziński,Mirosław Rucki,Marek Barlak,Piotr Konarski,Jakub Narojczyk,Zbigniew Werner

doi:10.3390/ma14020239

Abstract

The paper is dedicated to the life prolongation of the tools designed for deep-hole drilling. Among available methods, an ion implantation process was used to improve the durability of tungsten carbide (WC)-Co guide pads. Nitrogen fluencies of 3 × 1017 cm−2, 4 × 1017 cm−2 and 5 × 1017 cm−2 were applied, and scanning electron microscope (SEM) observations, energy dispersive spectroscopy (EDS) analyses, X-ray photoelectron spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) measurements were performed for both nonimplanted and implanted tools. The durability tests of nonimplanted and the modified tools were performed in industrial conditions. The durability of implanted guide pads was above 2.5 times greater than nonimplanted ones in the best case, presumably due to the presence of a carbon-rich layer and extremely hard tungsten nitrides. The achieved effect may be attributed to the dissociation of tungsten carbide phase and to the lubrication effect. The latter was due to the presence of pure carbon layer with a thickness of a few dozen nanometers. Notably, this layer was formed at a temperature of 200 °C, much smaller than in previously reported research, which makes the findings even more valuable from economic and environmental perspectives.

Highlights

We focused on deep-hole drilling tools
The performance improvement of the pads can be attributed to the reduction in the friction values of all implanted samples, caused by dissociation of the tungsten carbide phase
Results of technological tests in industrial conditions of guide pads in drilling heads for deep drills confirmed that nitrogen ion implantation of their working surfaces substantially increased tool durability

Summary

Introduction

The cemented tungsten carbides, patented in 1923 in England and in the USA, are typically composed of a hard tungsten carbide (WC) phase held together by a soft ductile binder phase, usually cobalt [1]. Because of a combination of attractive features, such as strength, hardness, fracture toughness, refractoriness, stiffness, resistance to compressive deformation and wear resistance even at higher temperatures, WC-Co tools are widely used for metal cutting, wood machining, rock drilling, etc. Numerous studies suggest that WC-Co damages can be interpreted as a continuous wear of the carbide during work of tools (or during mechanical tests) which leads to the formation of cracks in the material [5]. A variety of mechanisms have been proposed to describe the destructive phenomena in WC-Co, depending on the conditions of the work or laboratory tests [6,7]. A special case of the wear of WC-Co material is the corrosive wear, which may always occur in almost any environment, as several reports suggest [9,10]

Methods

Results

Conclusion