Passivation bending issue

All DMEs need to have a passivated surface. This means they must not have any open bonds. To archive this one usually resorts to the nonmetals of the fifth to seventh main group of the periodic table counting hydrogen to the seventh.

With the elements of the seventh group passivation is in most cases as easy as plugging every open bond wit a single hydrogen or halogenide atom. What makes this method undisirable in many cases is that those single bonds aren't very stiff to shearing forces. When two such surfaces slide along each other there is unnecessarily high dissipation meaning friction.

For sliding surfaces it is optimal when sixth row elements (Oxygen Sulphur) are used in such a way that the sliding direction lies in the plane spanned from the two bonds. Elements from group 15 (nitrogen, phosphorus) will work reasonably well.

The problem (or good thing) now is that atoms aren't perfect building bricks. If they "have" different numbrers of bonds they have different sizes. When a surface is passivated with group 16 elements (oxygen, sulfur) over a whole lengthe in the bonding plane direction it begins quite strongly to bend (distantly akin to a bimetal stripe).

To investigate: Could the elastic energy stored in strained structures reach dangerous levels? (fire / explosion hazard)

inner passivation of channels

Passivation bending can be troublesome when designing linear channels for sliding rails. To compensate the effect one can passivate the coplanar surface on the opposing side of a sheet of e.g. diamond exactly the same way. Alternatively to mend the effect one can alternate the surface passivation method (e.g oxygen/sulfur) in an regular or irregular pattern. In channels passivations with two valenced atoms the bond planes can be oriented normal to the channel axis.

There is designed a multi DME machine for ethine filtering from feedstock solution. It includes very tight channels
[Todo: analyze and discuss those]