In 1964, Bernard Schriever, commander of Air Force Systems Command and the architect of the Air Force’s ballistic missile and military space program, called the development of boron fiber “the greatest single advance in materials in the last 3000 years”.  His enthusiasm for its potential was attributed to boron fiber’s having a higher specific strength and stiffness (and most notably, a much higher specific compression strength) than any other structural material at the time.  Such high praise warrants a reflection on the development and use of boron fiber, a material still truly relevant nearly 60 years later.

Development of a High Strength High Modulus Boron Fiber first demonstrated in 1959.

While vapor deposition of boron fiber was first reported by E.J. Weintraub in 1911, Claude Talley and his co-workers at Texaco Experiments, Inc. are credited with first demonstrating the ability to make a continuous high strength, high modulus fiber via chemical vapor deposition in 1959.  This led to funding by the U.S. Air Force Materials Laboratory to develop the process further.  Initial contributors, along with Texaco, included United Aircraft Research Laboratory, Avco Systems Division, General Electric Research Laboratory, Monsanto, Batelle Memorial Institute, and others.  Only two companies were still standing by the late 1960’s: Avco Systems and Hamilton Standard, a division of United Aircraft Corporation. 

Avco Expands Boron Fiber Production to meet Demand for F-14 and F-15 Fighter Aircraft

Avco constructed a 10,000 lb./year production facility in 1970, purchased the Whittaker tape facility in 1971 to make B/Ep tape, and expanded the fiber production capacity in several steps to 30,000 lbs./yr. by the late 1970’s.  Both Avco and Hamilton Standard were supplying B/Ep tape to Grumman for the horizontal stabilizer of the F-14, and to McDonnell Douglas for the horizontal and vertical stabilizers and rudders for the F-15.  Other applications that developed include tubes for the mid-fuselage structure of the Space Shuttle Orbiter made by General Dynamics, the dorsal longeron of the B-1B bomber made by Rockwell, horizontal stabilizers for the Sikorsky H-60 Black Hawk helicopter, the Dassault Mirage 2000 rudder, and various sporting goods applications, including golf shafts, tennis rackets, and fishing rods.

Specialty Materials formed as a Privately Held Company to Continue Boron Fiber Business in 2001

By the early 1980’s Avco had become the lone supplier of boron fiber.  Hamilton Standard had been purchased by Composite Technology, Inc. and eventually closed its doors.  Textron purchased Avco in the late 1980’s.  Finally, in December 2001 Textron sold the boron business to a private investor and Specialty Materials, Inc. (SMI) was formed.

SMI Develops Gen 2 Hy-Bor®  as Boron Fiber Applications Expand

With the development of Hy-Bor® (a hybrid of boron and carbon fibers that optimizes the properties of both) in the 90s, boron applications expanded.  These included the General Atomics Reaper unmanned aerial vehicle (UAV), bicycle components and fly fishing rods.  Utilizing the positive CTE of boron fiber and matching it with the negative CTE of PAN or pitch-based carbon fibers resulted in very stable space structure components for optical imaging.  The recent development of Gen 2 Hy-Bor® has resulted in a greater choice of carbon fibers and resins and is generating interest in new applications including hypersonics and sporting goods.

In thinking back to General Schriever’s statement about boron fiber, is there any doubt we will see more new applications for boron fiber in the future?