The Silent Risks: Exploring the Potential Health Concerns of Tungsten Carbide-Co (WC-Co) Based Thermal Spray Coatings
- October 6, 2023
Introduction
Thermal spray coatings have evolved into innovative developments in the field of industrial progress, improving the effectiveness and durability of various materials. Tungsten Carbide-Cobalt (WC-Co) coatings have emerged as the most popular among them thanks to their exceptional toughness and resistance. Beyond their impressive qualities, however, is a lesser-known aspect of them that needs our attention: the potential health risks they pose to human health.
This article explores the core of the issue, illuminating the intricate details of WC-Co based thermal spray coatings, highlighting the cobalt carcinogenic link, and advocating for the adoption of strict safety measures. We emphasise the significance of striking a balance between industrial innovation and the welfare of the workforce and the environment as we reveal the silent risks. Join us on this journey as we explore the complex landscape of technology, health, and safety, working to ensure that advancement never comes at the expense of human lives or the sustainability of the environment.
What are WC-Co Based Thermal Spray Coatings?
Thermal spray coatings made of tungsten carbide and cobalt (WC-Co) are cutting-edge composite materials designed for exceptional hardness, wear resistance, and thermal stability. A precise ratio-mixing process is used to combine cobalt powder, a binder material, and the hard compound, tungsten carbide powder. The composite that is created by adding the binder, is then heated, and propelled onto a target surface using a thermal spraying gun. The molten or semi-molten particles solidify upon impact, forming a dense and durable coating. Due to their exceptional resistance to abrasion and high temperatures, these coatings are frequently used in industrial applications such as cutting tools, mining machinery, and aerospace components. This makes them essential for extending the life and performance of various tools and machinery.
Cobalt and Its Risks
The International Agency for Research on Cancer (IARC) has identified cobalt, a crucial component of WC-Co coatings, as a potential carcinogen (Torkashvand K., 2022). Long-term exposure to cobalt poses serious health risks, especially if it comes in the form of dust or fumes from manufacturing or grinding processes, which typically has a size range of 1 to 20 μm (Stefaniak A., 2009). Cobalt-containing particles that are inhaled or come into contact with the skin can cause skin rashes, respiratory issues, and, in extreme cases, lung and prostate cancer. After a number of epidemiologic studies revealed that hard-metal workers exposed to airborne WC and Co dust in occupational settings have an increased mortality from lung cancer, extensive research on genotoxicity and mutagenicity was carried out (Bastian S., et al, 2009).

Figure 1. Representative TEM images of A) non-exposed control cells, B) cells exposed to 100 μg/mL nano WC-Co for 12h, C) exposed to 100 μg/mL micro-WC-Co for 12 and D) exposed to 100 μg/mL nano WC-Co plus 10 μg/mL cytochalasin D for 12h. The arrows show WC-CO particles (scale bars = 0.5 μm) (Armstead, A. 2014).
Occupational Hazards and Safety Measures
Workers involved in the production, application, or maintenance of WC-Co coatings are particularly susceptible to the risks discussed in the previous section. Adequate safety measures, such as proper ventilation systems, personal protective equipment (PPE) like respirators and gloves, and regular health check-ups, are essential to mitigate these dangers. Employers must prioritise educating their workforce about the potential hazards and train them in safe handling practices (Huang H., 2016).


Environmental Impact
and Regulation
Workers involved in the production, application, or maintenance of WC-Co coatings are particularly susceptible to the risks discussed in the previous section. Adequate safety measures, such as proper ventilation systems, personal protective equipment (PPE) like respirators and gloves, and regular health check-ups, are essential to mitigate these dangers. Employers must prioritise educating their workforce about the potential hazards and train them in safe handling practices (Huang H., 2016).
Conclusion: Balancing Innovation with Safety
WC-Co based thermal spray coatings perform exceedingly well, but it’s important to understand and take precautions against any potential cancer risks. Strict laws, exacting manufacturing standards, and ongoing research into safer alternatives are necessary for achieving a balance between industrial innovation and the welfare of the workforce and the environment. By increasing awareness, implementing stringent safety measures, and supporting research, we can ensure that the wonders of technology do not endanger human lives or the sustainability of the environment.
Enter CoBRAIN
CoBRAIN, focused on advancing thermal spray coating techniques using novel formulations, exploiting versatility and low environmental impact of thermal spraying to produce alloy and hardmetal coatings as alternatives to the traditional Tungsten Carbide (WC)-Cobalt (Co) and Chromium based coatings, free of toxic and critical materials. The solution proposed by CoBRAIN is to develop novel hardmetals for thermal spray coatings based on compositionally complex systems of High Entropy Alloy and Carbides as binder and hard phase (respectively) and to support their application by a Sustainable Decision Support System to identify specific elements and process solutions optimised in different applications. In comparison to electroplated chromium, thermal spray coatings display a longer lifetime, less wear and corrosion degradation, and do not penalise the fatigue life of steel substrates.
References
- Torkashvand K., et al (2022), Advances in Thermally Sprayed WC-Based Wear-Resistant Coatings: Co-free Binders, Processing Routes and Tribological Behavior, Journal of Thermal Spray Technology, 31: 342-377.
- Stefaniak A., et al (2009), Characterization of exposures among cemented tungsten carbide workers. Part I, Journal of Exposure Science & Environmental Epidemiology, 19(5): 475-91.
- Bastian S., et al, (2009), Toxicity of Tungsten Carbide and Cobalt-Doped Tungsten Carbide Nanoparticles in Mammalian Cells in Vitro, Environmental Health Perspectives, 117(4): 530-6.
- Armstead A., et al, (2014), Exploring the potential role of tungsten carbide cobalt (WC-Co), Toxicology and Applied Pharmacology, 278(1):1-8.
- Huang H., et al, (2016), Physicochemical Characteristics of Dust Particles in HVOF Spraying and Occupational Hazards: Case Study in a Chinese Company, Journal of Thermal Spray Technology, 25: 971-981.