Resbond® 931C graphite adhesive

The choice depends mainly on the temperature and the mechanical stresses. Final Advanced Materials' high-temperature epoxy resins are generally limited to between 150 and 350°C, with satisfactory mechanical resistance (typical sheer-stress 10–30 MPa) and a degree of elasticity. However, the ceramic cements produced by Final Advanced Materials can be used up to 2,200°C, depending on the grade (alumina, zirconia, silicate, silica). They have excellent temperature resistance, but remain fragile (brittle behaviour, no elasticity). In the case of assemblies subject to differential expansion or vibration, epoxy is by far the preferred solution, if permitted by the maximum temperature of the application. However, in the case of extreme environments (kiln, vacuum, reducing atmosphere) which exceed 350°C, ceramic cement must be chosen.

The ceramic cements distributed by Final Advanced Materials have maximum working temperatures ranging between 650°C and 2,200°C. For example, alumina-based formulations often reach 1,650–1,760°C in an oxidising atmosphere. However, silicate systems are limited to around 1,000–1,200°C. The real maximum working temperature depends greatly on the environment (air, vacuum, inert gas), the time of exposure to this temperature and the thermal cycle (gradient, thermal shock). Specifically: the metal-loaded ceramic adhesives produced by Final Advanced Materials resist only up to the maximum temperature of the filler (650°C, for example, in the case of aluminium powder).

Yes, Final Advanced Materials produces epoxy resins loaded with silver, nickel or graphite with electrical conductivity (typical resistivity 10⁻⁴ to 10⁻³ Ω·cm) sufficient to enable a weld to be replaced. However, their temperature resistance is limited to 150–250°C under continuous temperature, or 300°C for short-term with thermal curing. Above this temperature the organic matrix degrades (under the effect of oxidisation and pyrolysis). NB: Final Advanced Materials' metal-loaded ceramic cements (nickel, aluminium or stainless steel) are not suitable for applications requiring electrical conductivity and high-temperature resistance (>350°C) because their electrical conductivity is far too low.

Ceramic/metal assemblies require often very different coefficients of thermal expansion (CTE) to be controlled. Final Advanced Materials recommends alumina-, silica- or zirconia-based ceramic cements for temperatures >350°C, which can bond to all types of ceramics and, generally, metals. For intermediate applications (≤350°C), an epoxy resin loaded with alumina powder enables thermal stresses to be absorbed and will be very compatible with different expansion coefficients. The thickness of the bond line must be between 100 and 300 µm to limit stress. Surface pre-treatment (sanding, degreasing, etc.) greatly improves adherence and is absolutely necessary if the CETs are very different.

The Cotronics adhesives distributed by Final Advanced Materials have variable cycles.

In the case of a cement, initial drying at ambient temperature takes between 2 to 24 h, depending on the viscosity and thickness. A thermal aftertreatment can be performed to allow them to attain their optimum properties after firing. Excessively rapid drying can lead to cracking or porosity in the cement.

Final Advanced Materials' epoxy adhesives which resist up to 260°C must be cured at ambient temperature. Epoxy adhesives which resist up to over 300°C require heat curing.

Graphite can withstand different temperatures depending on the atmosphere in which it is used. Its working environment directly affects its thermal performances.

In a vacuum or an inert atmosphere, graphite can withstand extremely high temperatures, even above 2,000°C. If oxygen is not present, the material retains excellent thermal and structural stability.

In air or an oxidising atmosphere, however, the maximum working temperature is lower. At around 400 to 500°C and above; graphite starts to oxidise gradually on contact with oxygen, leading to a degradation of its properties and loss of material.

Choosing the right graphite grade and considering the atmospheric conditions in which the graphite will be used is absolutely necessary to obtain the performance and lifetime needed for a given application.

The Final Advanced Materials team is at your disposal to help you choose the most suitable graphite solution based on your thermal and environmental constraints.

Due to its layered crystalline structure, graphite has excellent electrical and thermal conductivity properties.

This organisation facilitates the movement of electrons and the propagation of heat within the material.

However, graphite also has anisotropic properties: its conductivity varies depending on the direction of the crystalline layers. Conductivity is thus higher in the direction parallel to the layers than in the direction perpendicular to them.

Parameters such as the graphite's purity and density also influence its electrical and thermal characteristics. All these characteristics therefore determine the level of conductivity of the material.

Despite these variations graphite remains an excellent thermal and electrical conductor, which is particularly suited to many demanding industrial environments.

The Final Advanced Materials team is at your disposal to help you choose the most suitable graphite for your technical requirements.

Graphite is an excellent solution for aggressive chemical environments.

Due to its great chemical stability, it resists most acids and bases, including at high concentrations.

Unlike metals, graphite does not rust and does not dissolve in most corrosive environments, making it a material which is particularly suitable for demanding applications.

However, there are certain limitations which be taken into account. In the presence of oxygen and high temperature, graphite is subject to oxidisation which can impair its properties. In addition, in fluorinated environments, in particular in the presence of hydrofluoric acid, a direct chemical reaction with carbon can occur.

The choice of graphite and working conditions therefore depends on the application's chemical and thermal environment.

The Final Advanced Materials team is at your disposal to help you choose the best graphite for your technical requirements.

A graphite-loaded cement is a particularly suitable solution for repairing graphite parts.

Its chemical compatibility with the material, along with its thermal expansion and electrical conductivity, which are similar to those of graphite, make it a preferred solution for this type of application.

Ceramic-loaded cements are particularly recommended for localised repairs which do not require high a mechanical strength.

The Final Advanced Materials team is at your disposal to help you choose the best solution for your technical constraints.

Graphite naturally possesses lubricating properties which is one of its most widely acknowledged characteristics.

Due to its layered structure, where the different layers easily slide over one another, it is an excellent solid lubricant.

However, its performance can vary depending on the working environment. In an inert atmosphere or in a vacuum, its effectiveness diminishes due to the scarcity of gas and moisture, elements which make it easier for the graphite layers to slide over one another.

However, in an oxidising, high-temperature atmosphere the main challenge is its natural oxidisation, which can impair the graphite’s properties.

The choice of graphite therefore depends directly on the working conditions and on the constraints specific to your application.

The Final Advanced Materials team is at your disposal to help you select the graphite solution which is most effective and best suited to your needs.