Metallische und keramische Werkstoffe
Learning Targets
Understand critical concepts related to:
Pure metals: Characteristics and properties that make them suitable for medical applications.
Alloys: Types, characteristics, advantages, and specific usage scenarios in medical technology.
Ceramics and Cermets: Composition, structure, and their roles in implant technology and other medical applications.
Allotropy: Understanding phase changes in materials and their effects on performance in biomedical settings.
Elements used in medical applications: A survey of components that have significant biocompatibility and functionality.
Overall outline of the lecture content: A roadmap of the course covering all major segments of metallic and ceramic materials.
Overview of Materials in Medicine
Pure Metals:
Titanium (Ti): Known for its excellent strength-to-weight ratio, corrosion resistance, and compatibility with human tissue, making it ideal for implants and prosthetics.
Platinum (Pt): Valued for its inertness, used primarily for electrodes in cardiac devices and neurostimulators due to its reliability in biological environments.
Gold (Au): Used in dentistry for inlays, onlays, and crowns, gold is favored for its biocompatibility and resistance to oxidation.
Alloys:
Fe-Based Alloys: Alloys such as steel, made of iron combined with elements like chromium, nickel, carbon, molybdenum, and tungsten, offer high strength and are typically used in surgical tools and orthopedic devices.
Valve Metal Alloys: Titanium alloys are often combined with aluminum, vanadium, niobium, and palladium to enhance strength and reduce weight for use in implants.
Noble Metal Alloys: Include compositions like PtIr and gold alloys with copper, iron, silver, tin, and palladium, known for their excellent corrosion resistance and mechanical properties; they are used in sensitive medical applications.
Shape Memory Alloys: NiTi and NiTiCu demonstrate unique properties allowing them to return to a predetermined shape when thermally activated, suited for stents and orthodontic devices.
Co-based Alloys: Alloys such as CoCr and CoCrMo are employed for their biocompatibility and strength in joint replacements.
Mg-based Alloys: Added to expand possibilities in biodegradable implants to help reduce long-term medical complications.
Ceramics and Cermets:
These materials encompass oxides, nitrides, and carbides that exhibit high resistance to wear, heat, and corrosion.
Cermets: Examples include tungsten carbide and platinum-zirconium oxides, utilized in dental applications and joint prostheses for their hardness and biocompatibility.
Applications of Pure Metals
Titanium (Ti): Extensively used in implants, bone screws, and bone plates due to its strength and corrosion resistance.
Platinum (Pt): Functions include essential components such as electrodes for cochlear implants, pacemakers, and other medical devices where reliability is paramount.
Gold (Au): Frequently employed in dental restoration procedures such as inlays, onlays, and crowns for its excellent workability and biocompatibility.
Detailed Overview of Alloys
Definition of Alloy:
A mixture of two or more metallic elements or a combination of metals with nonmetals, characterized by limited ionic character, specifically engineered to enhance specific properties such as strength, ductility, and corrosion resistance.
Fe-Based Alloys: Primarily consisted of iron and alloying elements to improve performance in high-stress environments, especially in medical contexts.
Noble Metals Alloys: Renowned for their superior resistance to oxidation and corrosion, playing critical roles in devices such as stents and electrodes.
Allotropies in Metals
Iron (Fe): Exhibits different allotropes at various temperatures which are critical in determining its mechanical properties; the phases include alpha (α) at lower temperatures and beta (β) at higher temperatures, influenced by specific alloying elements.
Titanium (Ti): Transitioning between phases according to elemental stabilizers and temperatures, affecting its pliability and strength in applications.
Selection of Elements
Periodic Table Overview:
Elements from hydrogen (H) to oganesson (Og) examined with a focus on their applications and significance in biomedicine, particularly elements that exhibit favorable interactions with biological systems.
Importance of Noble Gases
A comprehensive discussion on the properties of noble gases and their roles in innovative medical technologies, notably in imaging and anesthesiology through inert behaviors and stability.
Focus on Salt-forming Elements
Examines the critical role of salt-forming metals in the formation of bioactive compounds and their myriad applications in medical formulations.
Toxicity Considerations
An overview of essential elements and their potential toxic effects in medical applications, emphasizing the need for careful material selection in implants and devices to mitigate health risks.
Adverse Effects of Metals
Discusses the negative impact that certain metals can have when utilized as implants, focusing on immune responses, inflammation, and metals leaching into tissues.
Chemical Substitution
Stresses the significance of chemical substitution to enhance the long-term stability and performance of implants within the physiological environment.
Functional and Metabolized Elements
Highlights the importance of understanding functional and metabolized elements in selecting optimal materials designed for medical uses, ensuring biocompatibility and functionality.
Solubility and Selection Outcomes
Analyzes how solubility, biocompatibility, and other physical-chemical factors influence the design and performance of biocompatible materials.
Candidates for Applications
Focuses on the material selection process, informed by specific roles in biomedical applications that must accommodate the dynamic biological environment.
Considerations for Candidates
Discussions center around materials that dissolve easily and demonstrate desirable mechanical and biologic behavior under physiological conditions, ensuring their suitability in long-term medical applications.
Medical Applications and Structures
A broad overview of lecture topics covering crucial areas such as crystal structures, electrochemical properties, and specific materials like precious metals such as titanium and cobalt-based alloys.