The internal radiation hazard
Alan Martin, Sam Harbison, Karen Beach, Peter Cole in An Introduction to Radiation Protection, 2018
Working surfaces should be finished in hard non-porous materials which have the necessary heat- and chemical-resisting properties. The most commonly used materials include the following: Melamine resin plastic laminate such as Formica®. It should be bonded to the backing material with a resin glue to give the necessary temperature resistance.PVC sheet, such as Darvic, which can be welded and is completely self-extinguishing.Stainless steel, but there is a tendency to get physical bonding between it and corrosion products. Also, stainless steels are susceptible to attack from certain chemicals, for example hydrochloric acid.Glass fibre–reinforced resin which can be moulded to shape. This can be treated to make it fire resistant.Modern man-made compounds such as high-pressure laminates (e.g. Trespa®) and advanced composites (e.g. Corian® Polypropylene), which can be welded and heat-formed.
Biomedical Devices: Overview
Jack Wong, Raymond K. Y. Tong in Handbook of Medical Device Regulatory Affairs in Asia, 2018
Lightweight, strength, and biocompatibility are the key requirements for the material to be chosen for medical implants. The most commonly used orthopedic implant materials are stainless steels, cobalt-chromium alloys, and titanium alloys [13]. Stainless steel is often preferred for making bone plates, screws, pins, and rods because of its resistance to chemicals and environmental conditions found inside the human body. Cobalt-chromium alloys are used in joint replacement and fracture repair implants. Titanium alloys have a significantly higher strength-to-weight ratio than stainless steels. The higher flexibility offered by titanium alloys allows the design of shape-memory-based implants to aid in bone in-growth for better grip. Trabecular metal, which is made from tantalum over carbon, is also strong, flexible, and biocompatible and is porous enough to allow tissue in-growth. Ceramic materials are also used to make implant surfaces that rub each other but do not require flexibility, such as the surface of the hip joint [14].
Guidewires
Vikram S. Kashyap, Matthew Janko, Justin A. Smith in Endovascular Tools & Techniques Made Easy, 2020
Core Material: Stainless steel and nitinol are the primary materials found in the core of wires. Stainless steel is generally stiffer, providing the user with greater ability to steer the guidewire tip and superior support, while flexible enough to navigate tortuous vessels; this material also retains its shape better, conveying greater durability (2). Stainless steel can generally be found in the cores of support/working wires (e.g., Amplatz, Lunderquist) used to carry large endografts (thoracic endovascular aortic repair [TEVAR], endovascular aneurysm repair [EVAR]) where a stiff guide is paramount to ensuring these devices track safely and reliably into place. Nitinol is known for being malleable and highly flexible. Malleability allows better navigation along more tortuous vessels while flexibility allows it to be resistant to kinking, which would prevent further passage down a vessel (2). Such nitinol cores are useful in specialty wires used to navigate tortuous vessels, or cross-complex lesions, conveying good support with the flexibility to track and cross, establishing initial access to be used for wire exchange or device delivery. Wire cores can be either homogenous in their material construction or heterogeneous with transitions from proximal to distal (usually stainless steel at the shaft and nitinol at the tip).
The era of biofunctional biomaterials in orthopedics: what does the future hold?
Published in Expert Review of Medical Devices, 2018
Mubashar Rehman, Asadullah Madni, Thomas J. Webster
Metals and metal alloys were the first materials to be used as orthopedic devices in the form of plates, wires, rods, pins, needles, and screws. They were exclusively used for weight bearing parts of the body due to biocompatibility and desirable mechanical properties. Metal alloys are a mixture of metals wherein the basic properties of the metals are changed (Table 1). For orthopedics, commonly used stainless steel contains chromium (Cr, 17–20%), nickel (Ni, 12–14%), molybdenum (Mo, 2–3%), and carbon (C, 0.03%) [14]. Cr is added to stainless steel to make it resistant to corrosion caused by a diverse biological environment due to the spontaneous formation of a Cr2O3 layer. Ni gives an ‘austenitic’ structure which contributes strength and toughness. Mo also imparts corrosion resistance especially that which is caused by electrolytes such as chlorides. C is added for strength and hardness. Stainless steel also contains a minor amount of nitrogen, manganese, sulfur, phosphorus, and silicon. Ni-free stainless steel was prepared with high Cr content (20%) where manganese (Mn) and nitrogen (N, 0.3%) were used to make the austenitic structure.
High variability in toxicity of welding fume nanoparticles from stainless steel in lung cells and reporter cell lines: the role of particle reactivity and solubility
Published in Nanotoxicology, 2019
Sarah McCarrick, Zheng Wei, Nynke Moelijker, Remco Derr, Kjell-Arne Persson, Giel Hendriks, Inger Odnevall Wallinder, Yolanda Hedberg, Hanna L. Karlsson
It is estimated that 11 million workers worldwide have welding as their primary occupation, and a total of 110 million people are somehow exposed to welding fumes at their work settings (IARC 2017). Some of these welders are exposed to stainless steel welding fumes. Gas shielded metal arc welding (GMAW) is one of the most common universal industrial practices (Praveen, Yarlagadda, and Kang 2005), in which an electric arc is formed between a consumable wire fed through the welding gun and the base metal. This arc creates sufficient heat to melt and join the metallic surfaces together. A shielding gas is added to provide suitable conditions for the arc and the metal transfer as well as to protect the weld from contaminants and to eliminate slag formation. Welders choose welding conditions, such as potential, current, arc mode, melting rate, filler material feed rate, and choice of shielding gas, based on, among others, the base material and its thickness. The vaporized material generated in the welding process oxidizes and results in a fume mainly containing agglomerates of nanometer-sized primary particles of metals and metal oxides (Mei et al. 2018). The composition of the fume is largely dependent on whether a stainless steel or mild steel base alloy is welded. Stainless steel is an iron (Fe)-based alloy that contains at least 11wt.% chromium (Cr) as well as, depending on grade, other alloy elements such as nickel (Ni), manganese (Mn), and molybdenum (Mo) to achieve particular characteristics and making it considerably more resistant to corrosion compared to mild steel.
Protocol with non-toxic chemicals to control biofilm in dental unit waterlines: physical, chemical, mechanical and biological perspective
Published in Biofouling, 2022
Rachel Maciel Monteiro, Viviane de Cassia Oliveira, Rodrigo Galo, Denise de Andrade, Ana Maria Razaboni, Evandro Watanabe
Product A showed the greatest tendency to corrosion of stainless-steel samples. According to current density, Product B and Product AB had a similar curve and were statistically similar to the control. As the corrosion process develops, the chemical molecules that compose a material are transformed by their electrochemical reactions. In addition to oxidation, which implies the loss of electrons, reduction can promote an increase in the number of electrons (Gentil, 1996). Corrosion is the result of a process of the environment in each material, causing surface damage. Furthermore, electrochemical corrosion is a spontaneous process, which occurs in an aqueous environment when the metal is in contact with an electrolyte, in which anodic (electron loss) and cathodic (electron gain) reactions occur simultaneously (Revie and Uhlig 2008). Generally, 316 L stainless steel is attractive for biomedical applications due to its excellent corrosion resistance (Hryniewicz et al. 2009). It should be noted that the corrosion experiments in this study extrapolate the reality that would be carried out in dental clinical practice regarding exposure time and concentration of products with the dental unit components made of stainless steel, for example triple syringes and high-speed handpieces.
Related Knowledge Centers
- Alloy
- Chromium
- Corrosion
- Iron
- Surgical Instrument
- Nickel
- Carbon
- Self-Healing Material
- Chemical Plant
- Cleanability