Introduction to hydrogen treatment technology of titanium alloy materials

Hydrogen treatment technology of titanium and its alloys is a relatively active research direction in the field of materials science and engineering. At present, hydrogen treatment technology has been applied in research on thermal processing, mechanical processing, powder consolidation, composite material preparation, microstructure refinement, etc. of titanium alloys, and has formed a unique research field. The use of hydrogen treatment technology to improve the superplastic properties of titanium alloys is an important research aspect. So far, many scholars have used the hydrogen treatment effect to improve the superplastic properties of cast titanium, deformed titanium alloys and titanium-aluminum intermetallic compounds.
At present, there are two ways to use hydrogen treatment technology to improve the superplasticity properties of titanium alloys:
(1) Utilize the plasticizing effect of hydrogen, add an appropriate amount of hydrogen before superplastic forming of titanium alloy, increase the proportion of B phase in titanium alloy, reduce the flow stress during superplastic deformation, and achieve the purpose of improving the superplastic properties of titanium alloy.
(2) Hydrogen treatment is used to refine the microstructure of titanium alloys, and combined with plastic deformation technology to prepare ultra-fine-grained titanium alloys, so that titanium alloys have excellent superplastic properties at lower deformation temperatures and higher deformation rates.
Modern superplastic deformation theory believes that grain boundary slip is the main mode of superplastic deformation, and diffusion and dislocation movement within grains and grain boundaries are the main coordination mechanisms of grain boundary slip. In the superplastic forming of titanium alloys, the B phase is dominated by diffusion creep or dislocation creep; the A phase is dominated by grain boundary slip, coordinated through diffusion and dislocation motion; the flow between the A and B phases is dominated by A Completed with B phase boundary migration. Hydrogen mainly plays the following roles in the superplastic forming of titanium alloys:
(1) The addition of hydrogen improves the diffusion ability of alloy elements, leading to the enhancement of diffusion creep of B phase and intergranular slip of A phase.
(2) The diffusion of hydrogen activates the pinned dislocations, promotes the climbing and sliding of dislocations, improves the sliding ability of B grains, and is conducive to the dislocation coordination required for A/A grain boundary sliding.
(3) The weak bond effect caused by hydrogen reduces the diffusion activation energy, enhances the atomic diffusion ability, and improves the superplastic flow ability.
(4) It can be seen from the Ti2H phase diagram that the addition of hydrogen significantly reduces the B\A+B transition temperature and increases the volume fraction of the B phase, which directly leads to the improvement of plasticity and the reduction of flow stress, allowing titanium alloys to Superplastic forming is performed at lower deformation temperatures and higher deformation rates.

Read More

Titanium rod filter use and cleaning method

Titanium rod filter, titanium rod is made of sintered titanium alloy powder. The filtered product has the characteristics of solid-liquid separation, particle removal, heat source removal, high clarity, and good mechanical and physical properties. It is mainly used for decarbonization of medicinal liquid, and can replace the traditional sand rod filter in the production of large infusion. After long-term use, customers have consistently reported that the effect is good, and all technical indicators meet the requirements of the Pharmacopoeia and GMP.

Precautions for using titanium rod filter:
1. Avoid scratches, collisions, dust and oil.
2. The working pressure should not exceed the rated working pressure during use.3.During normal use, there is at least 3-5 minutes of low-pressure start-up time, and the relative pressure difference should be controlled below 0.5Mpa, and then the working pressure should be gradually adjusted to normal needs (the maximum pressure should not exceed 0.4Mpa).
4. After the product has been working for a certain period, it may be due to the clogging of the filter element, which may cause the pressure to increase and the flow rate to decrease, requiring backwashing or backwashing regeneration. Regeneration cycle depends on rated pressure and flow rate


Titanium rod filter cleaning method:
After the titanium rod filter element is used for a period of time, it will produce a certain degree of blockage, which means that the flow rate decreases and the pressure at the front end of the filter increases, such as: from below 0.22mPa to above 0.3mPa, then the filter element must be cleaned. There are the following types:
1. For the newly used filter element, it is generally cleaned by water backflush and gas backflush, that is, clean water slightly higher than the working pressure (eg; 0.3mPa) is injected in the opposite direction for cleaning. Recoil time is about 1 to 3 minutes.
2. After repeated backwashing, when the filtration effect does not improve significantly, it can be soaked in a hydrochloric acid solution below 5%, or a sulfuric acid solution below 8%, or a NaOH solution below 10% at room temperature, and then washed with water.
The specific choice of pickling or alkali washing should be based on the fact that the impurities in the filtrate are easily soluble in acid or alkali.

Read More