Materials Processing, MT20006 Powder Processing of Materials Abhishek Sarkar 1 Lecture 1, 11 March 2024 Introduction Properties Alumina: Al2O3 Characterization Processing Performance Structure Alumina powder *General question: What is the physics behind these changes in the optical features? 2 Callister, Materials Science and Engineering: An Introduction, 2007 Other open web sources Lecture 1, 11 March 2024 Powder Processing of Materials: Learning Objectives 1. Why powder processing over other techniques? 2. What is the powder processing route? 3. How powder processing is relevant for different kinds of materials (metal, ceramics, etc.)? 4. How can properties be altered via different powder “processing” parameters? Part 1 Introduction and motivation (applications) Part 2 Basics of relevant characterization techniques Part 4 Powder processing in ceramics Part 3 Powder metallurgy (fabrication + processing) Part 5 Powder processed thin films *Please note that the terms “Powder Metallurgy (P/M)” and “Powder Processing in Materials” will be used synonymously! 3 Lecture 1, 11 March 2024 Powders Iron pillar via P/M In P/M, “powders” are particles that are typically smaller than 1 mm! 4 https://old.iupac.org/publications/ci/2005/2706/3_veazey.html Lecture 1, 11 March 2024 What is powder processing of materials (or P/M)? Powder Fabrication Powder Processing/Compaction Mechanical fabrication (machining, milling, etc.) Electrolytic fabrication Chemical fabrication (precipitation, decomposition of solid) Atomization techniques (gas-, water-, centrifugal-based) … Sintering Coating Molding Additive Manufacturing … Application (Properties) *If needed, the entire process could be in solid-state 5 Lecture 1, 11 March 2024 P/M tetrahedron What parameters can we vary to achieve suitable properties? Properties/Performance Characterization Structure/Chemistry Processing Powder Fabrication 6 Lecture 1, 11 March 2024 Why powder processing of materials? Differences of powder metallurgy (P/M) from other metal processing techniques Most of the techniques other than P/M involves mechanical forming (ductility) or melting! **For ceramics and other inorganic non-metallic systems powder processing is actually most commonly used approach 7 Callister, Materials Science and Engineering: An Introduction, 2007 Lecture 1, 11 March 2024 Advantages of Powder Processing (or P/M) Captive: Materials difficult to process by other techniques (like casting) ➢ Metals with high melting points (refractory metals/alloys: W, Mo, Zr, Ti, etc.) ➢ Metals/alloys with low ductility and formability (SmCo5, Nd2Fe14B, W, etc.) ➢ Basically, all ceramic (non-metallic inorganic) materials (oxides, carbides, borides, etc.) Nd2Fe14B permanent magnet in hard drives 8 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Battery electrodes Lecture 1, 11 March 2024 Advantages of Powder Processing (or P/M) Economic for complex parts (“precision + cost”) ➢ High quality complex parts with close tolerance (net shaping) ➢ High production rates ➢ Pre-alloyed powders + processing below melting (phase segregation issues like in casting can avoided) 9 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Lecture 1, 11 March 2024 Advantages of Powder Processing (or P/M) Unique microstructures ➢ Porous materials ➢ Oxide dispersion strengthened alloys ➢ Ceramic-metal composites, cemented carbides Porous stainless steel filters 10 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Lecture 1, 11 March 2024 Applications of Powder Processing (or P/M): Automotive Industry Electric Vehicles 11 https://www.youtube.com/watch?v=AhHe4UjXhoc Nature Energy, Volume 3, pages 267–278 (2018) Lecture 1, 11 March 2024 Different powder based (processing) technologies: Automotive Industry Traditional P/M (sintering) ➢ Gearbox parts, engine parts, brake system Powders for Additive Manufacturing (AM)/ 3D printing ➢ Topology optimized light weight constructions ➢ Repair ➢ Integration and optimization of functions Futuristic applications ➢ E-motors: high performance magnets ➢ Fuel cells and battery components AM based E-drive housing for Porsche Processing techniques Powders for coating ➢ Wear resistance, protective coating for thermal load ➢ Repair Powders for Metal Injection Molding ➢ High precision (for complex components) ➢ Good surface quality and cost effective Adjustment rings for Variable-geometry turbochargers 12 https://www.youtube.com/watch?v=AhHe4UjXhoc Lecture 1, 11 March 2024 Overview of P/M Properties and Applications Powders as precursor for several advanced processing techniques like additive manufacturing (3D printing), metal injection molding, powder based thin-film deposition, etc. Structural application Functional applications ➢ Corrosion resistant ➢ Electrical and electronic applications ➢ Applications involving refractory metals ➢ Energy related applications ➢ Friction and wear rated applications ➢ Catalytic applications ➢ High temperature applications ➢ Controlled porosity applications ➢ High hardness applications ➢ Magnetic applications ➢ High and low density applications ➢ Biomedical applications ➢ Radiation absorber based applications ➢ Thermal (heat-removal) applications ➢ ….. ➢ ….. **Not an exhaustive list 13 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Lecture 1, 11 March 2024 Overview of P/M Properties and Applications: Structural Components ➢ Good tolerance control and net shaping: Dimensionality control (± 0.025 mm) ➢ Density control of 0.1 g/cc ➢ Strength control ± 35 MPa, elongation scatter ± 2 % 14 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Lecture 1, 11 March 2024 P/M Properties and Applications: Controlled porosity ➢ Control of pore size and pore connectivity ➢ Filters, flow restrictors, oil-less bearing, corrosion resistant biomedical implants 15 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Journal of Materials Science & Technology, Volume 76, Pages 129-149 Lecture 1, 11 March 2024 P/M Properties and Applications: Magnetic Materials ➢ Most of the hard magnetic materials are brittle compounds (SmCo5, Nd2Fe14B, SrFe12O19, etc.) *General questions: What are hard and soft magnetic materials? And where are they used? 16 Lecture 1, 11 March 2024 P/M Properties and Applications: Magnetic Materials Typical P/M based Nd2Fe14B fabrication 17 Manufacturing Processes for Permanent Magnets: Part I—Sintering and Casting, Volume 74, pages 1279–1295, (2022) Lecture 1, 11 March 2024 Summarizing: Why Powder Processing (or P/M)? Important characteristics of powders: relatively high surface area to volume ratio Powder can flow under gravity and fill up space like liquids ➢ High volume production of precise, high quality structural parts (especially from ferrous alloys) ➢ Consolidation of high performance material where “full density” and reliability are of primary concern ➢ Fabrication of difficult to process materials (with unique microstructures) ➢ Economical consolidation of specialty alloys ➢ Synthesis of “metastable” materials (like nanomaterials, metallic glasses) ➢ Processing of complex parts (with unique ingredients/ uncommon shape) ➢ Ceramics and composites processing are largely powder based 18 Randall M. German, Powder Metallurgy Science, 2nd Edition, 1994 Lecture 1, 11 March 2024 Books to follow ➢ Powder Metallurgy Science by Randall M. German (Chapter 1: Introduction to Powder Metallurgy, Chapter 11: Properties and Applications) ➢ Materials Science and Engineering: An Introduction by William D. Callister (Chapter 11: Applications and Processing of Metal Alloys) ➢ Other references in the respective slides 19 Lecture 1, 11 March 2024
