Adhesion at metal–ZrO2 interfaces

Active metal brazing of zirconia

Wetting of ceramic materials by liquid silicon, aluminium and metallic melts containing titanium and other reactive elements: A review

Zirconia stabilized with yttria was bonded to a Ni-based superalloy by active brazing. An interlayer with the composition of the silver–copper eutectic plus 1.75 wt.% titanium was used as brazing material. Various brazing heating cycles were performed using a furnace with graphite heating elements and under flowing argon. The microstructure of the bonded couples is related to the chemical reactions occurring during the brazing cycles, to the properties of the specific compounds formed and to the interdiffusion phenomena occurring across the interfaces. Critical feature for the success of the joint is the nature of the interfaces that the brazing interlayer formed with the superalloy and the zirconia. At the interface with the superalloy adhesion is obtained under a relatively wide range of experimental conditions. On the contrary, at the interface with zirconia, a good wetting and adhesion occurred only when a titanium oxide sublayer with a specific thickness formed. The best results were obtained with a maximum temperature between 870 and 900°C, a soaking time of 10 min and a fast heating rate (10°C/min). The optimal thickness of the TiO x sublayer was less than 1 μm.

Bonding of zirconia to super alloy with the active brazing technique

Joining yittria stabilized zirconia (YSZ) to Ni–20Cr (NiCr) was fabricated using YSZ–NiCr functionally graded materials (FGM) interlayer by hot pressing process. The thermal properties of this YSZ–FGM–NiCr joint were studied by thermal cycling testing and shear testing. Microscopic observations indicated that the graded distribution of the composition and microstructure in the joint eliminate the macroscopic ceramic/metal interface. The joint shows good thermal stability and good oxidation resistance up to 1000 °C. The thermal fatigue cracks initiate and grow in the way of aggregation of microvoids and their connection in the YSZ-rich NiCr–75 vol.%YSZ interlayer during the thermal cycling to 1000 °C. However, these discontinuous cracks in interlayer release the thermal stress and avoid spallation in the joint interface of direct ceramic/metal bonding. No spallation was found in the joint with three interlayers of 2.0 mm theoretical thick each after 30 thermal cycles. The shear strengths were found to be 207.0 and 75.0 MPa in NiCr–50 vol.%YSZ and NiCr–75 vol.%YSZ interlayers respectively for this joint after 30 thermal cycles.

Fabrication and thermal properties of a YSZ-NiCr joint with an interlayer of YSZ-NiCr functionally graded material

The contact angles of Zr-Ni, Zr-Cu and Zr-Co alloys against PSZ were measured by the sessile drop method. Each alloy wetted PSZ very well. Zr-Co alloys showed a different behaviour. Joints of PSZ plates were obtained using Zr-17Ni alloy. At the joint interface, internal oxidation of zirconium occurred. The fracture shear strength of this joint was 55 MPa.

Joining of zirconia using zirconium-based alloys

Joining of zirconia to metals using Zr-Cu alloy

On a caracterise l'etat chimique de l'interface entre de l'acier au carbone et une zircone stabilisee par Y 2 O 3 apres reaction solide-solide a l'aide de plusieurs methodes spectroscopiques (TFXD, RPE et XPS)

Interfacial reaction between zirconia and carbon steel

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Reaction of Zirconia with Carbon Steel in a Vacum Condition

/pdf/reaction-and-interfacial-characterization-on-joining-of-3n3hx5xbq4.pdf

Hajime Yokoo

Papers

Joining of zirconia using zirconium-based alloys

Joining of zirconia to metals using Zr-Cu alloy

Interfacial reaction between zirconia and carbon steel

Reaction of Zirconia with Carbon Steel in a Vacum Condition

Reaction and Interfacial Characterization on Joining of Zirconia to Carbon Steel(Materials, Metallurgy & Weldability)