Carbolite launches microwave assisted furnace

Carbolite is developing the microwave assist technology (MAT) furnace in collaboration with C-Tech Innovation Ltd, based near Chester in the UK, a leading specialist in microwave-assisted heating technology. The first model will be a chamber furnace with a maximum operating temperature of 1600°C with 23 litre capacity. In addition to the conventional radiant heat generated by the furnace elements, up to 1.8kW of power is generated by an industrial 2450 MHz magnetron.

Unlike radiant heat, which is conducted from the outer surface of a sample to the interior, microwaves generate heat immediately within the body of the material. This combined approach produces faster processing rates than both radiant-only and microwave-only systems, and therefore reduces energy usage, throughput times and emissions.

More consistent properties can also be achieved in some materials, including greater strength, improved yield and reduced formation of undesirable phases. Processors can also take advantage of the selective heating characteristic of microwaves.

The design of the furnaces combines the controllability of the radiant elements with the thermal equalising effect of the microwave heating system.

The controller allows 20-segment programming of both the radiant and the microwave heating, giving users a high degree of flexibility. Over-temperature protection is also included.

Successful applications for microwave-assisted heating include precious metals assaying, burning off wax castings moulds and sintering high-performance ceramics such as zirconia, where benefits include very consistent grain size.

While scaling up microwave-only systems from laboratory to production capacities can be difficult because of the problem of maintaining high power densities over a large area, MAT heating furnaces can be scaled up relatively easily.

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Redevelopment of high vacuum end seals

Originally the high vacuum end seals were developed for the vacuum tube furnaces (HVT range). On these particular models one end of the strengthened work tube is connected to a high vacuum pump, while the other end has a removable stainless steel flange to both hold the vacuum and allow samples to be inserted and removed. These particular flanges were offered as accessories on standard tube furnaces, as they could seal at extremely low vacuums (10-5 mbar). The down side was that they were extremely large and heavy.

The end seals work by a combination of three plates pulling together, with the centre one being threaded. They all pull together to force the internal rubber 'O' rings between both the individual plates and the work tube in order to form an airtight seal.

The range of high vacuum end seals was redeveloped in order to make them more suitable for use as an accessory with standard tube furnaces. Development was concentrated on reducing the size and weight of the end seals, as well as improving the way they seal with the work tube. A good example of this development was on the seal that fits a 75mm I.D. tube; the physical size has been halved and the weight was reduced from 4kg to 1kg. These improvements make the vacuum end seals easier to handle, as well as putting less stress on the product and work tubes.

There are vacuum seals to fit a large range of tubes with an OD of between 26 and 170mm, the ID/ OD ratio is included in the product code.

As well as the significant range of size options, the end seals can be supplied with plain or vacuum manifold ends, with either option having the ability to include internal water cooling to protect the rubber 'O' rings from overheating. There is also the possibility to include gas inlet or thermocouple glands if required.

New controllers!

As part of Carbolite's continuing development, we will be upgrading from the Eurotherm 2000 series of controllers to the 3000 series. This includes the redevelopment of the Carbolite 300/301 controllers jointly designed by Carbolite and Eurotherm.

Carbolite 301
This three term (PID) microprocessor based temperature controller includes an adjustable ramp rate to setpoint, either up or down, and a process timer button for either a controlled process duration or a delayed start
It is a high precision instrument jointly designed by Carbolite and Eurotherm.

The measured temperature is displayed by large LED's in a wipe clean membrane panel
The temperature setpoint, ramp rate and countdown time are adjusted at the touch of a button
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