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Is Rotary Friction Welding a good method to join cylinders of a metal (such as Ti alloy) and a ceramic (such as SiC).

I know that Diffusion bonding can be used in such cases. However, it has its own disadvantages - particularly its time-consuming nature.

In this context has the use of rotary friction welding (or some other friction welding process) suitable?

It is clearly suitable for shape. But are the materials themselves amenable to this? Since friction welding relies on softening the materials by heating; the dissimilar ductility and thermal properties (SiC is particularly high melting) may pose problem.

I found this which suggests that this is possible but cautions that material selection is important for determining suitablity.

Full Disclosure:

This problem was inspired by a problem on one of my engineering exams. At the time of asking, the exam had already ended a day ago, so asking this question does not (in my understanding) pose any ethical issues.

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  • $\begingroup$ I think Niels is right. But if you did manage to melt the ceramic, that is of course without friction (stir welding), then somehow quickly brought it to a ready FSW’ed metal like aluminum then maybe they would weld, but after cooling I believe the metal would cause fracture of the ceramic. Edit: that still wouldn’t work because that’s not how the metal would weld to the melted ceramic, if anything it would just be melted ceramic that would just solidify around & near the interface and because the metal is cooler then believe the ceramic would still fracture. Too bad we cant access the flowing $\endgroup$
    – L92MD14
    Commented Jul 16, 2021 at 17:45

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Probably not. The friction welding process presupposes a certain level of ductility so the mating surfaces can deform together and completely bond. Ceramics lack the deformation mechanisms that metals have and so one would not expect bonding to easily occur. In addition, getting the workpieces hot enough to melt by friction requires tremendous pressures squeezing them together during the process, which would most likely cause the ceramic to fail in compression and shear and shatter to pieces.

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  • $\begingroup$ Citation needed? Quick google search shows ceramics can melt, so why is it so straightforward that they would break before melting? $\endgroup$
    – fpjxmqjtaw
    Commented Mar 9, 2021 at 16:57
  • $\begingroup$ @Sevron, as I stated in my answer, ceramics are not ductile, and if loaded hard they shatter instead of deforming. in this case, the heat required to melt the materials comes from friction, which means that before they get hot, they experience huge stresses by being forced together with huge pressure while rotating. this will almost certainly shatter the ceramic long before it gets hot enough to melt. $\endgroup$
    – niels nielsen
    Commented Mar 9, 2021 at 17:43
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    $\begingroup$ It is a forge weld; nothing melts. At high temperature the components are forced together and some is extruded from the joint ; not possible with SiC. Titanium would be a very poor candidate as it would absorb oxygen and nitrogen from air at high temperatures. $\endgroup$
    – blacksmith37
    Commented Jul 16, 2021 at 18:06

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