June 17, 2012
On St. Patrick’s Day, a holiday significant to engineers in the USA, I wrote about the prominence of that profession within my family. It so happens that I’ve had occasion to expand upon that on another holiday. I’ve never really been big on Father’s Day, despite having four children of my own, but on the usual phone call to my father we got to talking about his background in electron microscopy. He was not only a pioneer applying it to materials engineering, but also involved in education, looking to produce the next generation in his field, particularly from Nigeria.
Dad pointed out to me that much early use of electron microscopes came from the biological sciences, in developing precise topologies for organic samples. After graduating in Materials Engineering at the American University in Cairo, with a mind towards metallurgy, and some industrial experience in that speciality from work in Sheffield, he arrived at Case Western Reserve University in the middle of a minor revolution. A cadre of young materials scientists and engineers including Dad’s mentor, Dr. Terry Mitchell, were revolutionizing the field by paying attention not just to broad, observed behaviors of materials, but also what was happening at the molecular and even atomic level, using electron microscopes.
The old guard, including Professor John Wallace, Head of Department and ridiculed the new direction as fiddling about aimlessly with atoms, hardly likely to yield much practical insight of materials. My father characterized Prof. Wallace as “a WWII colonel, and a holdover from traditional blacksmithing.” I could recognize in Dad’s voice that this was a gentle teasing that barely masked the respect he held for a man whose achievements bridged two domains where my Dad recognized honor: the forge, and the battlefield (he had himself been an officer in the Biafran army).
At any rate, the skeptics soon had to give credit to the youngsters’ methods, as under Dr. Mitchell’s tutelage these Ph. D. students were making significant discoveries at a stunning rate, especially by unlocking the mysteries of the complex behaviors of different compounds of silicon under oxidation. Dr. Mitchell had brought along his reputation for applying electron microscopy to silicon carbide (carborundum), ceramic and zirconium oxides, etc. Dad quickly focused on silicon dioxide (silica) and its ceramic derivatives. Sometimes the mystery was the overall properties of the materials, such as why silicon carbide is the second hardest material after diamond, and how it can withstand such high temperatures (over 2000 °C) and even then doesn’t melt but rather decomposes.
The key concept here is the phase of materials. Most people only concern themselves with the three commonly known phases of matter: solid, liquid and gas. An additional phase, plasma, has gained mainstream recognition lately, whether hot plasmas such as flames, lightning and solar flares, or cold plasmas such as the wandering particles of deep space. Materials experts can’t afford such simplicity. In their dealings with solids they recognize many sub-phases. Ice, for example has four separate, natural phases, depending on temperature and pressure. Each phase is a different structure of the molecular lattice. Some materials, such as the ones Dr. Mitchell and his students worked on, have innumerable phases.
One of the odd class of toys on which I grew was the foam-and-ping-pong-ball models of molecular lattices you could find strewn wherever my Dad was preparing coursework, representing specific molecular structures from crystallography, and which were at the foundation of the materials work through electron microscopy. Indeed I always remember how brilliantly Dad could explain to me, an eight or nine year old, the chemistry, physics and general significance of whatever he was working on or teaching at University level and beyond. Later I became aware of his reputation in Florida and Nigeria as a stern but brilliant lecturer, who produced far more keen students than circumstances would lead one to expect. I count myself an early beneficiary.
The Case Western department was of engineering, not science, so there was always pressure to find immediate application for their discoveries. In fact the accusation of overly pure and dainty research was at the heart of the old guard’s initial skepticism. As it happened, the practical effects of the electron microscope studies were legion, not just in the emerging field of semiconductors (the phase of a material can dramatically affect its dielectric and diamagnetic properties), but also in terms of withstanding high temperatures. It was this latter concern that led Dad, after receiving his Ph. D., to the University of Florida at Gainesville, and into the circle of one of his era’s great triumphs in materials engineering: the space shuttle tiles. These prevent the shuttle from burning up in reentry, and the terrible Columbia tragedy but underscores the marvel of the technology. It was but a minute loss of integrity that led to the destruction of the entire craft, such is the enormous burden of heat on a re-entering vehicle.
Dad didn’t work directly on the tiles, but he collaborated closely with the engineers who did, especially at an regular conference in Cocoa Beach, to which he would often take his family. I sat in some sessions, including one in which the space shuttle tiles were demonstrated to top materials engineers in attendance in the form of a lightweight, heat-proof jacket. At Gainesville my father focused on the oxidation of silicon carbide and made a key discovery: the reason for the material’s heat resistance is that does oxidize, but a special oxide layer forms almost immediately on the surface with such properties that it prevents the oxygen from further incursion into the material, regardless of the temperature. This layer is so incredibly thin (a few ångströms) that it took not only electron microscopy but also expert preparation, sectioning the sample in a proper transverse manner that allows the oxide layer to be discovered.
Despite all this exciting work, Dad was compelled to head back to Nigeria, now in the middle of an oil boom, and with many of the wounds from the Biafran war seemingly on the mend. He knew that his space-aged research would hardly be applicable back home, but he had high hopes for a teaching career producing brilliant chemical and materials engineerings, as Dr. Mitchell had done. Unfortunately the oil boom was a sugar-coated curse. The country deteriorated in every way as government, industry and even students succumbed to cash-rules thinking. The effects of such misdirected ingenuity are still globally notorious in the form of “419” Internet scams.
After ten years Dad returned to the USA, and started not far off where he left off as a research fellow at The NASA Lewis Research Center. There he found that many of the mysteries he had left off concerning rates of re-oxidation of silicon oxides and nitrides had not been solved in his absence, and he set about continuing his earlier work, with gratifying success until NASA’s budget cuts pushed him into retirement in the early 2000s.
As I wrote in the St. Patrick’s Day post, Dad’s legacy is not only in seeing my brother and me into the engineering profession (though we went with the electronics and computing variety), but also inspiring my cousins Brian and Ubu (the latter deceased tragically young) through materials engineering doctorates. This is especially poignant considering that when he left Nigeria after the war he hadn’t even heard of materials engineering. He’d been looking to read applied mathematics, and ended up taking the first available scholarship that suggested an eventual path to graduate studies in the USA. Materials engineering is not the most widely heralded field, but it makes possible an astonishing number of our modern conveniences, from electronics to airplane parts, from medical devices to safety glass and security barriers. There is still a chance that Nigeria, with its embarrassment of riches in raw materials, can someday become a producer of the most advanced materials, and if so these early Ph. D.s will surely be vindicated.
These days when one of my children asks me a question about the natural world, I put everything down and don my teacher’s cap, using analogies, models built of legos, detective stories from the history of science, characters from their favorite cartoons, whatever it takes. That is the echo from my father, the immaterial phase which, as I am reminded this Father’s Day, matters more than anything else.