Burlington, Ontario, January 21, 2014 – VAC AERO has recently shipped a horizontal vacuum furnace to the Centre de Metallurgie du Québec (Québec Metallurgy Centre), a research institute affiliated with the Trois-Rivières college in Québec.

The VAH2636 HV-2 furnace will be housed in a new a state-of-the Art facility in Trois-Rivières. The chamber size is 23” X 18” X 36” (WHL) with a metal hot zone designed for operating at temperatures of up to 2400°F. The furnace operating systems is based on VAC AERO’s versatile HC900 interactive hybrid control package with SCADA and complete network integration capabilities and remote monitoring and control.

Erosion is defined in the AWS Brazing Handbook (published by the American Welding Society in 2007) as follows: “Erosion is a condition caused by the dissolution of the base metal by the molten brazing filler metal, resulting in a reduction of the base metal thickness.”

Thus, the phrase “base-metal erosion by the brazing filler metal” is used to describe a process in which a molten brazing filler metal (BFM) which is highly soluble in a given base-metal (parent metal), is applied to the surface of that base metal, is heated to brazing temperature, and in so doing, actively diffuses into that base metal, alloying extensively with (dissolving) it. by Dan Kay

This month I’m going to take a step away from vacuum pumps and systems and write about general applications that use vacuum in the process. There may be some applications you have heard about and some, hopefully, that may be new to you. Whenever a vacuum (a pressure lower than the surrounding atmospheric pressure) is used in a process it will generally fall into one of the Five Main Reasons for using Vacuum. In some cases a process may use vacuum for two of the five reasons. This month I will discuss the first of these reasons, in no specific order.

1. To Provide a Working Force.

First, a short explanation of the two vacuum measuring units used in this article. We know that standard atmospheric pressure is 14.7 lbs. in^-2 and that your real life atmospheric pressure varies up and down a few percentage points from the standard depending on a) weather conditions in your area and, b) your altitude above sea level. By Howard Tring

One of the most serious limitations to Vickers hardness testing in the micro-load range (10-1000 gf or 0.098-9.81 N) has been the variability in measured hardness with loads ≤ 100 gf (≤ 0.98 N). In the literature four HV-load trends have been reported for this range.  In the order of most common to least common, the trends are: the hardness decreases with decreasing load; the hardness increases slightly and then decreases; the hardness increases with decreasing load; and, the hardness is constant. Many publications have concentrated on the most common trend and attributed it to material factors. Samuels [1] stated, however, that these problems were due to microscope limitations, such as limited contrast and resolution, and visual perception limitations. At the same symposium, Westrich [2] showed that the SEM could be used to measure small Vickers indents and yield virtually constant hardness as a function of load. By George Vander Voort

Because So Much Is Riding On Us! Heat treating aircraft landing gear involves experience, precision and state-of-the-art equipment.Because of our ongoing commitment to excellence recognized by customer approvals from major Aerospace prime contractors, we’re proud to be one of the world’s largest subcontractors for processing landing gear components for commercial and military aircraft. The basis…

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There are virtually no cases of naturally occurring color in meteoritic microstructures.  Color can be introduced using DIC but it has no physical significance or value.  Polarized light may produce some color effects with graphite and certain mineral phases but these are not commonly observed.  Crossed polarized light, in some instances, can produce color effects in coarse martensite within taenite wedges, as shown in Figure 1.  This is a high magnification micrograph of coarse martensite in Odessa using nearly crossed polarized light and a sensitive tint plate (which has colored the residual taenite magenta).

The best approach to create meaningful color micrographic images is to “tint” etch the specimen, sometimes after performing a light etch with picral or nital.  A tint etch [1] produces a stable film on the specimen surface whose thickness depends upon the composition (and variation in composition) of the phase, its crystal orientation, the presence of residual strain, and etch time.  Tint etchants are classified as being anodic, cathodic or complex, depending on the nature of the film that forms.  Anodic tint etchants, the most common type, produce films over the matrix phase, such as kamacite in meteorites.  Cathodic tint etchants produce films over the second phase constituents, such as cohenite.  Complex tint etchants will produce films over both matrix and second phases (but not necessarily over all types of second phases present). By George Vander Voort

Last time the discussion was about throughput and conductance in vacuum systems. This time we will look at the pressure profile throughout the vacuum system in a slightly different way than it was shown last time. The first thought might be that once the vacuum system is under vacuum carrying out the process, the lowest pressure will be in the vacuum chamber and that the highest pressure will be at the primary pump exhaust which will be atmospheric pressure. As we see from Fig. 1, this is not quite correct.

Fig. 1 shows how the pressure changes through the system and actual values of P pressure and S speed are given in the table, Fig. 2. The pressures shown assume that the chamber has been evacuated (pumped down) to the process pressure needed and conditions are stable. By Howard Tring

Although liquid-penetrant inspection, such as dye penetrant inspection (DPI) and fluorescent penetrant inspection (FPI), are useful tools for inspecting fusion-welds, they should NOT be used for inspecting brazed joints.  This is especially true for any parts on which subsequent braze-repair may be required, such as many aerospace components that are vacuum-brazed, then placed in service for long periods of time, and then come back for later repair or rebuilding and then sent back out for more field-service.

DPI and FPI have long been used in the welding industry, and should certainly continue to do so, since weld-cracks and surface imperfections can readily be seen by these techniques and subsequently repaired without difficulties. by Dan Kay

The history of vacuum technology is a fascinating one. It seems to have begun in ancient Greece when the philosopher Democritus (circa 460 to 375 B.C.) proposed that the world was made up of tiny particles that he called atoms (atomos, Greek: undividable). Democritus proposed that empty space (in other words, in modern terminology, a vacuum) existed between the atoms, which moved according to the general laws of mechanics. Democritus, together with his teacher Leucippus, may be considered as the inventors of the concept of a vacuum. Our modern view of physics is heavily influenced by the ideas of Democritus.

However, it was the thinking of Aristotle (384 – 322 B.C.) that dominated the scientific community up until the 16th century. Aristotle denied the existence of a vacuum as it conflicted with the idea that the universe was comprised of countless individual particles. According to Aristotle, nature consisted of the four basic elements namely water, earth, air, and fire.  In fact, the word vacuum comes to us from the Latin word “vacuus” meaning empty or “vacare” meaning “to be empty”. By Dan Herring