As an actor for almost 20 years in the field of 3D printing ceramics, the CTTC has naturally followed the latest technologies to enhance its services to companies. With nearly 2 million Euros invested in new equipment and related development projects in connection with additive manufacturing of parts and ceramic components, the technological panel and expertise available through CTTC-Alterinov is unique in Europe.

The Alterinov platform, located in the heart of the Ester Technopole in Limoges already has seven additive manufacturing technologies, a dozen of printers and ancillary means of material preparation, thermal treatment and control.

Technologies 

3D printing by binder jetting

3D printing by binder jetting onto a powder bed consists of four steps:

• Deposit of a thin layer (50 to 300 µm) of powder on the work surface;
• Lamination of this layer by a roller or a scraper;
• Projection of binder droplets by an ink jet printer head in the desired pattern;
• Downward movement of the work surface to the equivalent of a layer thickness and steps (1) to (4) are repeated.

After complete manufacture of the part, it is cleaned by simply removing the "unbound" powder with a brush or an air jet. This method does not require the construction of support, as it is provided by the powder bed itself.

Binder jetting technology is particularly interesting for applications requiring a low operating cost since it is primarily related to the powder placed in the machine and powders that are not directly consumed for the production of the part can be recycled. In addition, this technology achieves the highest production speeds to date (up to 20 l / h) and the manufacturing of large volumes of parts. These advantages are to be balanced with the need to use large particle-size powders and the residual presence of porosity in materials.

Applications: membranes, refractory materials, bone substitutes, tableware, etc.

LASER stereolithography

After the research conducted by SPCTS (Laboratory of Ceramic Processes and Surface Treatments Sciences), this 3D ceramics manufacturing technology uses the principle of laser stereolithography (SLA): the object is built in layers using a UV laser that polymerizes a paste made of photosensitive resin and ceramic. The shaped composite is then subjected to thermal treatment to remove the polymer and then sinter the ceramic.

This technology is particularly well-suited for the manufacture of technical parts in zirconia, alumina or calcium phosphate with mechanical properties comparable to those obtained by conventional shaping methods.

*The CTTC entrusted 3DCeram with the exclusive manufacture of ceramic parts using the SLA process (patent FR0201599).

Applications: Jewellery, watches, cranial implants, etc.

Selective LASER sintering

The selective laser sintering (SLS) process consists of four steps:

• Deposit of a thin layer (60 to 150 µm) of powder on the work surface;
• Lamination of this layer by a roller or a scraper;
• Movement a laser beam of at least 200 W for selectively sintering a two-dimensional pattern;
• Downward movement of the work surface to the equivalent of a layer thickness and steps (1) to (4) are repeated

After complete manufacture of the part, it is cleaned by simply removing the "unbound" powder with a brush or an air jet. It then undergoes optional firing in a conventional oven to complete the sintering of the material.

The laser sintering method, which also uses a "powder method", provides similar advantages to the binder jetting process with the main difference being that the part is partially or fully sintered during construction. This technology reduces the production time of parts (no short firing cycle or thermal post-treatment) and produces parts on the printer close to the final dimensions (near-net-shape).

**The CTTC works with the ENSCI (National School of Industrial Ceramics) on SLS technology

Applications: refractory materials, membranes, implants, etc. 

Micro-extrusion printing

FDM (Fused Deposition Modelling) technology has its equivalent in the field of ceramics by using a screw extruder or piston into which a paste loaded with ceramic particles is introduced. The extrusion die, usually of small diameter, is controlled to deposit a pattern on a flat substrate with a filament of paste and then the operation is repeated for the top level.

This simple and inexpensive technology enables the development of ceramic parts with high mechanical properties. The thickness of the layers is generally 0.4 to 1 mm, which allows high-speed construction, but poor dimensional accuracy.

Applications: artistic porcelain pieces, tableware, ceramic filters, etc. 

Ink jet printing

The inkjet printer is a contactless dot matrix printing technique where fine ink droplets are ejected on a planar substrate. Inkjet printing can be divided into two categories: continuous jet and drop-on-demand.  ***The inkjet printer available at the CTTC is the CERADROP brand and is based on the drop-on-demand process. In this technique, the printing module is constituted of a row of nozzles, which can be controlled separately. A piezoelectric actuator is used to trigger ejection.

The inkjet technology generates three-dimensional structures layer by layer by successive deposition of micro-droplets (a few picolitres) of a ceramic, metallic or polymer system from trajectory files obtained after treatment of the overall volume of the part, defined by CAD. Inks containing materials dry after impact on the substrate, which form the layer. Several layers can be stacked in this manner with different materials to build, layer after layer, a 3D multi-material component.

Applications: components for electronics, antennas, sensors, metallic or ceramic tri-dimensional patterns or surface functionalisation, etc. 

Aerosol jet printing

Aerosol jet printing (AJP) is a direct printing technology for depositing a wide variety of materials: metals, polymers, ceramics, composites, biological inks, etc. It uses a specific nozzle to generate a stream of collimated droplets (liquid aerosol), which is controlled to deposit the ink in a predefined pattern on a substrate. Subtle patterns can be obtained by placing a controlled shutter under the nozzle.

AJP technology is very flexible: it is suited to flat surfaces, but also curved and textured surfaces, and cavity or vias filling. It can be used for low and high viscosity inks and allows the production of narrow (10 µm) and wide (1 mm) lines, and the creation of 3D patterns.

Applications: conductive tracks, deposit of solder, sensors, texturing and surface functionalising, etc. 

Direct energy deposit of ceramics

The CTTC develops the first additive manufacturing technology by direct energy deposit, suitable for ceramics. INPACT (Inorganic Nanostructured Parts by Cold Aerosol Technology) is a proprietary method for producing delicate three-dimensional patterns on any medium (metal, glass and plastic). The deposited ceramics have a dense microstructure (>99%) with no thermal treatment required.

Contact us for details.