Admittedly my belief in the existence of a bond between a steel insert cast into an aluminum housing is based on field experience rather than experience with the manufacturing process. I do have an interest in the manufacturing process, which I pursue from the comfort of a La-Z-boy. My enthusiasm for the manufacturing process may or may not add value to this discussion.
The contention that no known method exists to bond aluminum to iron is not consistent with the experience of folks who die cast aluminum. It is my understanding that the unintentional adhesion of aluminum to the ferrous die material is a substantial challenge for manufacturers. My understanding of the bond is that under specific conditions a reaction between the iron and aluminum results in the formation of a composite material, an intermetallic interface, which both iron and aluminum adhere to.
Whether this method or some other is purposefully used in manufacturing is ultimately the question. In my experience, evidence of a bond’s existence is strong in an aged, well used assembly showing no evidence of fluid incursion. Typical failures involve fluid (lubricant) incursion between the materials, working the joint apart over time as it is thermally cycled. Joints which have not failed show little or no evidence of fluid incursion when field tested by warming the component and inspecting the joint for fluid weepage.
Consider the application of the steel insert cast into the left crankcase. Prior to 1990 this insert supported the Big Twin’s left main bearing. With no bond between the crankcase and insert, the dissimilar expansion of the steel and aluminum would result in internal joint movement, wear and eventual fluid incursion.
If in this example no bond exists between the steel insert and aluminum crankcase, explaining the affect of joint expansion, the resulting wear and fluid incursion on the long term durability of the joint would likely be an interesting read.
djkak
You are a thinker and you are also thinking into the future just a bit. NASA is right now in the process of setting up metallurgy experiments in space to research these very subjects. Experiments of metal deposition are currently being set-up using an electron beam gun in space - a natural cryogenic chamber - to begin some extensive studies toward some of these types of alloys and surface adhesion problems that exist on the planet in our limited ability to create the correct isolated environment. The ability to alloy elements in space where temperature and vacuum work to change the eutectic properties of elements is going to be amazing - to put it mildly.
This laboratory where I work is involved in some of these studies and experiments as well. This lab has an accelerator that is one of the worlds only continuous electron beams - studies of matter down to quarks and their adhesion. The main ongoing research is into the area of "what is holding molecules and their sub parts together" or "what is the glue that is holding matter together"? (as soon as they know, teleportation will become a reality - "beam me up Scotty"). To go a little farther, I'm involved with the fabrication of the niobium cells that house and form the electron beam for the accelerator and our chief problem is forming the perfect cell (shaped like bells, electron beam welded together (we have a Sciaky Electron Beam Welding Chamber) at their equator and iris to form electron guns varying in size, shape and length). Niobium is very expensive but it is the only metal that becomes a superconductor at super low temperature (-465 degrees) so it becomes invisible to an electron. And, in our quest to develop an alloy of an easily formed metal along with the superconducting characteristic of niobium, some experiments with joining elements such as iron, aluminum, copper, titanium, and others together and to niobium.
Hoping not to bore you with a lot of detail, we have experimented with a bond of aluminum and different alloys of steel. They act like oil and water an will bond or mix to an extent but there always remains a junction boundary line that will separate when the article is subjected to a temperature change. Oil and water will mix when a wetting agent (soap) is entered into the mix. Steel and aluminum will also emulsify in a very controlled area of temperature but as soon as the temperature changes these elements begin their rejection and the molecules begin to coagulate into a glassy, super thin layer that has no malleability or elasticity so it becomes the boundary line that fails during cooling and solidifying. So, the 'emulsified' or alloyed metals lose their desirable qualities - such as emulsified oil and water - the water loses its surface tension and oil loses its ability to lubricate and then will begin to separate once again. The desire is to form a gradual emulsion or alloy from one material to the other and at present, we have not done this.
Some of the physicists at this lab could use these 'ideas' that folks think about and also would benefit with the 'is possible' attitude that some of us have. Science fiction becomes science fact when scientists forget about what they conceive as impossible.
I guess until there is a better way developed to join iron and aluminum, we will have to depend on some engineers' conception of a well designed 'spiny lock' and strive to prevent the joint from becoming a rattling, slipping and leaking mess.
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Topic: 110 Cylinder Liner Movement (Read 16057 times)