What is Spark Plasma Sintering

California Nanotechnologies - Intro to Spark Plasma Sintering

Spark Plasma Sintering (SPS) is a sintering technique used to fabricate dense and homogeneous bulk materials from powders. It involves the application of pulsed direct current (DC) and uniaxial pressure to the powder within a die. The DC current passes through the powder and generates a plasma discharge between the particles, causing rapid heating and sintering. The SPS process typically takes place in a vacuum or controlled atmosphere environment to prevent oxidation and ensure purity. The temperature, pressure, and heating rate can be precisely controlled during the process, allowing for the fabrication of materials with unique microstructures and properties. SPS has found applications in a variety of fields, including materials science, nanotechnology, and engineering. It is commonly used to fabricate ceramic, metallic, and composite materials with high density, fine grain size, and enhanced mechanical, electrical, and thermal properties. SPS has several advantages over traditional sintering methods, such as high heating rates, short processing times, and low sintering temperatures. These advantages result in reduced energy consumption and cost, improved material properties, and increased efficiency in the manufacturing process.

What is Spark Plasma Sintering

Spark Plasma Sintering “SPS” (aka FAST or Field Assisted Sintering Technology) is an advanced technique to take powder and turn it into solid parts similar to additive manufacturing but without having to melt the material. It allows for the rapid application of temperature and pressure via high-density pulsed current within a controlled atmosphere. The unique heating mechanism of using electrical current gives SPS the ability to consolidate materials that traditional processes can’t and at much faster rates. SPS is the ideal consolidation and bonding method for all of your materials including metals, refractory alloys, nanomaterials, ultra-high temp ceramics, and more. In simple terms, SPS can be thought of as a way of making strong and dense materials from powders using high heat and pressure.

Click here to listen to the latest episode of the Materialism podcast which features our CEO Eric Eyerman talking about Spark Plasma Sintering!

Overall Benefits of SPS

Shorter Cycle Times - Sintering cycles are minutes vs hours/days for conventional processes. High productivity, extremely rapid material development capabilities.
Lower Sintering Temperatures - Sinter materials at lower temperatures compared to conventional sintering processes
Extremely Versatile - Densify low melting point metals, ultra-high temperature ceramics, or even bond dissimilar materials requiring nonuniform temperature. No other sintering process can come close. Can sinter porous parts and fully dense parts.
High-precision process control - Able to finely control sintering parameters including temperature and pressure to ensure the best outcome for your parts. Unique chemistries are unable to be made with conventional liquid melt processes. Engineered structures within materials preserved that would otherwise be lost in other processes

SPS & Powder Metallurgy:

Spark plasma sintering (SPS) is a cutting-edge technique within the powder metallurgy industry, revolutionizing the fabrication of advanced materials. It involves applying high electrical current and pressure to compact powder particles, resulting in rapid consolidation and sintering. This process enables the production of high-density components with fine microstructures and enhanced mechanical properties, making it invaluable for manufacturing applications in aerospace, automotive, electronics, and healthcare sectors. By significantly reducing processing time and energy consumption while maintaining superior quality, SPS contributes to the advancement of powder metallurgy as a versatile and efficient manufacturing method, meeting the increasing demand for high-performance materials in various industries.

Just a few applications of SPS

Energy Storage: High-capacity lithium-ion batteries and other advanced energy storage materials
Biomedical Engineering: Porous ceramics for drug delivery and scaffolds for tissue engineering
Advanced Ceramics: High-temperature superconductors and high-performance piezoelectric ceramics
Intermetallics: Advanced alloys with improved mechanical, thermal, and electrical properties
Composites: Reinforced ceramics and metals with enhanced mechanical properties

Diffusion Bonding using SPS

Not only can SPS densify powder materials but it is also highly effective at bonding both similar and dissimilar materials together. Bonding can be performed with all the materials listed above and more. Options for bonding include:

Bulk solid to bulk solid materials
Powder to solid
Bonding thin sheets together
Functionally graded material bonding (ceramics to metals, polymers to metals, etc.)

Additional resources to learn about SPS/FAST:

Fast-SPS Booklet 2023
https://onlinelibrary.wiley.com/doi/full/10.1002/adem.201300409

https://www.sciencedirect.com/topics/engineering/spark-plasma-sintering

https://www.totalmateria.com/page.aspx?ID=CheckArticle&site=kts&NM=460

Classification	Materials for SPS processing
Metals	Virtually any metals possible: Fe, Cu, Al, Au, Ag, Ni, Cr, Mo, Sn, Ti, W, Be
Ceramics	Oxides Carbides Nitrides Borides Flourides	Al2O3, Mulite, ZrO2, MgO, SiO2, TiO2, HfO2 SiC, B4C, TaC, TiC, WC, ZrC, VC Si3N4, TaN, TiN, AiN, ZrN, VN TiB2, HfB2, LaB6, ZrB2, VB2 LiF, CaF2, MgF2
Cermets	Si3N4+Ni, Al2O3+Ni, ZrO2+Ni Al2O3+TiC, SUS+ZrO2, Al2O3+SUS SUS+WC/Co, BN+Fe. WC+Co+Fe
Intermetalic compounds	TiAl. MoSi2, Si3Zr5,NiAl NbCo, NbAl, LaBaCuSO4, Sm2Co17
Other materials	Organic materials (polyimide, etc.), compositematerials

Spark Plasma Sintering Podcast

In this video, Cal Nano's CEO discusses Spark Plasma Sintering on the Materialism Podcast. We cover Cal Nano's history with SPS, the latest advancements in the field, and answer important questions about SPS technology. A great listen for those wanting to learn more about how to use SPS for advanced material research and manufacturing