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| Development of the injection molding of YG10 cemented carbide with microcry-stalline waxy binder |
| YANG Yu1，2，YUAN Jiankun1，2，CHEN Pengqi1，2，LANG Hongbin3，HUO Junhao3，
CHENG Jigui1，2 |
| （1.School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China; 2.Engineering
Research Center of Powder Metallurgy of Anhui Province, Hefei 230009, China; 3. Chengdu Bangpu
Cutting Tools Co., Ltd, Chengdu 611731, China） |
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Abstract To overcome the shortcomings of conventional injection molding with paraffin based binder for cemented
carbide, such as easy phase separation, unstable property of feedstock, slow debinding rate and poor shape conformation,
a binder system with microcrystalline wax (MW) as the main component was employed to injection
mold WC-10Co (YG10) cemented carbides. The optimized parameters of mixing, injection, debinding and sintering
were investigated to obtain YG10 cemented carbides with excellent performance. WC and Co powders were
mechanically premixed, then added into an internalmixer with microcrystalline wax (MW), high density polyethylene
(HDPE), stearic acid (SA) and some other binder components according to the ratio. Banbury mixing was performed
at 180 ℃ for 2 h. After crushing and screening, the resultant feedstocks were added into the injection machine
for injection molding to get green bodies. The binder in the green bodies were removed by a combination of
solvent debinding and heat debinding. The debinded compacts were sintered in a vacuum furnace. Effects of injection
temperature, pressure and other process parameters on the density and surface defects of the injected green
bodies were investigated, and the debinding behavior of injected green bodies under different debinding solvents
and different debinding temperatures was studied. Thermogravimetrics was performed on the injected green compacts, and suitable heating debinding process was developed. Furthermore, by changing the mass fraction of carbon
black in sintering filler, sintered YG10 cemented carbides samples with excellent performance were obtained. The
experimental results show that the density of injection body increases first and then decreases with the increase of
injection temperature, and increases first and then stabilizes with the increase of injection pressure. The debinding
speed of the sample in trichloroethylene solvent is higher than in kerosene sovent, and the suitable solvent debinding
temperature is about 35 ℃, resulting in a higher solvent debinding rate and flawless samples. The binder in the
green compacts can be completely removed by the thermal debinding process of slowly rising temperature and
holding heat at 200, 350, 450 and 650 ℃ respectively. The sintered body with excellent properties can be obtained
by vacuum sintering at 1 400 ℃. Under the conditions of injection temperature 150 ℃, injection pressure 11 MPa
and mold temperature 40 ℃, the injection molding body with high density and defectless can be obtained. After solvent
debinding and heat debinding, YG10 sintered bodies with relative density of 99.5%, bending strength of 2 019
MPa, hardness of 91.7HRA and cobalt magnetism of 8.76 Gs·cm3/g can be obtained by vacuum sintering at 1
400 ℃ for 90 min.
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Received: 06 December 2021
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Corresponding Authors:
程继贵（1963—），男，教授，主要研究方向为先进粉末冶金材料及工艺技术。
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2022, Vol. 32 
